VaST [Variability Search Toolkit]

A software for variable star detection
on a series of astronomical images

Contents
What is VaST?
Screenshots
VaST mailing list
Download
Short usage notices
Output files produced by VaST
Publications using VaST
Other useful tools

VaST is a software tool for finding variable objects on a series of astronomical images. The images (CCD frames or digitized photographic plates) must be taken with the same instrument using the same filter and saved in the FITS format. The images may be shifted and rotated with respect to each other, but they have to have the same scale (arcsec/pix). VaST performs object detection and aperture photometry using SExtractor on each image, cross-matches lists of detected stars, performs magnitude calibration with respect to the first (reference) image and constructs a lightcurve for each object. The simple sigma-magnitude plot may be used to visually identify variable star candidates. If data permit, period-search techniques ANOVA and BLS may also be employed to identify periodic variable stars among the candidates. All lightcurves are being constructed in an arbitrary magnitudes. If there are reference stars with known magnitudes in the field of view, all magnitudes can be later converted to the standard system.

Unlike software based on the image subtraction method, VaST can be used in case of unstable PSF (e.g., bad guiding, digitized wide-field photographic images). VaST is not tied up to any catalog and WCS, so it can be successfully used on images taken with a telephoto lens as well as with a 2.6-m class telescope.

VaST is written in C (and partly in BASH scripting language) for GNU/Linux operating system. The latest versions are also tested on MacOS X. The program is in a continual, albeit slow, state of development. VaST is free software: you can redistribute and/or modify it under the terms of the GNU General Public License.

To compile and use VaST you'll need:
  • GNU/Linux or MacOS X and some skills in using it
  • GCC (including Fortran and C++ compilers), comes with your GNU/Linux distribution
  • BC calculator (can be found in your GNU/Linux distribution)
  • cURL (can be found in your GNU/Linux distribution)
  • SExtractor. If SExtractor is not installed system-wide, VaST will use the built-in SExtractor v2.5.

You can find at this page the latest version of VaST (download via ftp or http, ~7.3M) along with some sample data (ftp or http, 24M)
and a short PowerPoint presentation in Russian (2M) which covers some aspects of variable star search with VaST (very, very, I mean VERY old!).

Files described here as well as older versions of VaST are available via our anonymous FTP.

Special note for Ubuntu users! The following installation procedure is recommended:
  • Install SExtractor (version 2.5 is recommended, DO NOT use the version of SExtractor supplied with Ubuntu, it is known not to work) and GSL from the source code.
  • Install a number of additional libraries (including PGPLOT) from pre-compiled Ubuntu packages:
    sudo apt-get install build-essential gfortran g++ libX11-dev libXi-dev libXmu-dev libpng-dev pgplot5 curl wget
  • Compile VaST.
For version before vast-1.0rc63.tar.bz2 note, that after installing GSL from the source code it may be not visible for VaST at runtime. If VaST compiles well, but fails to start due to missing GSL library, execute
export LD_LIBRARY_PATH=/usr/local/lib # Default location of the GSL library installed from the source code
before running VaST.

Special note for MacOS X users! The latest version of VaST was tested on MacOS X 10.8.2 'Mountain Lion' with XQuartz, Xcode, MacPorts installed in the system and gcc, gfortran, g++, and wget installed through MacPorts.

Screenshots

Different subroutines in VaST may be started automatically from the main program or manually by a user from a terminal. Names of the corresponding executable files are given under each screenshot. Click on images to see them in high resolution:


The variability search window
./find_candidates

The lightcurve inspection program
./lc


VaST (the main program) running in a terminal
./vast

VaST FITS image viewer
./pgfv

Video (screencast)
voice comments are in Russian only, sorry... I hope to prepare an English version soon...
Download, compile and test VaST

download this video in full resolution (11M)
How to identify variable stars with VaST

download this video in full resolution (29M)

How to remove trend from a lightcurve

download this video in full resolution (29M)

VaST mailing list

If you would like to receive updates about new versions of VaST, please enter your e-mail address in the form below

or just drop a line to kirx[at]scan.sai.msu.ru

Compiling VaST

First, make sure that you have PGPLOT, CFITSIO and GSL libraries installed in your system. Then unpack the program
tar -xvjf vast-latest.tar.bz2
cd vast-1.0rc64
And try to compile it by running
make
If compilation fails, read carefully compilers output. Most probably it can't find some necessary libraries. Explore the Makefile with a text editor and change the libraries location to match your environment.

Using VaST

To try VaST, download the sample data set, unpack it
wget -c ftp://saistud.sai.msu.ru/pub/vast/sample_data.tar.bz2
tar -xvjf sample_data.tar.bz2
change to the VaST installation directory and run the program
cd vast-1.0rc64
./vast ../sample_data/*fit
or
cd vast-1.0rc64
./vast ../sample_data/*fit
After a brief computation the variability search window will be opened. Click on any star on the sigma-magnitude plot to inspect its lightcurve. Click on any point on the lightcurve plot to see an image from which this point comes. The star on the image will be marked with a red cross, a red circle around the star corresponds to the aperture used to measure this image.

If you quit the program without deleting any data, you can restart it without doing all the computations again by running:
./find_candidates aa

To calibrate the magnitude scale using comparison stars in the field of view use this script:

util/magnitude_calibration.sh
It will ask you to specify one or more comparison stars and their magnitudes. After the comparison stars have been specified, close the image window with the right mouse click and inspect the relation between instrumental and catalog magnitudes. This relation may be fitted by a linear function with the slope fixed to 1, linear function with a free slope, second degree polynome (parabola) or the Bacher et al. (2005, MNRAS, 362, 542) magnitude calibration relation (this one is suitable for digitized photographic plates). Use (P) key on your keyboard to change the fitting function. For most CCD data sets, linear function with the fixed slope provides a good fit. The data points may be weighted according to their estimated errors or weighted equally. Use (W) key to change weighting. Close the dialog with the right mouse click to apply the calibration to all stars when you are satisfied with the fit.

In order to save the current work, use the script

util/save.sh my_favorite_field_name
If the field name was not provided, the script will ask for it. To restore previous work, use
util/load.sh my_favorite_field_name
or just copy all saved files from directory [my_favorite_field_name] back to the VaST directory.

To delete all files from the previous work, you can use:
util/clean_data

There is a tool to automatically identify variable stars detected with VaST. It requires a working Internet connection at runtime. The tool may or may not work for your field depending on luck. If the field of view is greater than, say, 30' and the image quality is fine - the odds that the automatic plate solution will work for your field are pretty good. Here is how to use it... To identify the star number 00190 in the current dataset use the following command:

util/identify.sh out00190.dat 25
where "out00190.dat" is the lightcurve file of the star and "25" is the estimated field of view size in arcminutes. It is wise to set this value a little bit smaller than your best-guess field of view. If no field of value is given, the default value of 40' will be assumed. Note, that the field of view identification may take really long time (up to ~30 minutes), especially for small fields. Please, do not interrupt the process - just wait for a result. If the field identification failed, try to restart it with smaller estimated field of view size. On successful identification, the script will print the equatorial coordinates (J2000) of the star and will attempt to query popular databases to check if this star is already known as a variable. Note, that the coordinates returned by the identification script may be up to 10" off. We strongly advise to use the Aladin interactive sky atlas to verify the identification and obtain more precise star coordinates from some astrometric catalog (e.g., USNO-B1.0). The automatic identification function relies on tools provided by Astrometry.net. For more details visit http://astrometry.net/. Note, that according to the use conditions of the index files required to run the Astrometry.net code, you need to be ready to share the images solved using this software with any other interested party including the Astrometry.net team. According to the same use conditions: "If the indexes are used in any scholarly work, research grant proposals or other scientific or academic publications, the Astrometry.net project must be properly cited and acknowledged. The paper to cite is the Lang et al paper on our bibliography page http://astrometry.net/biblio.html. The acknowledgment text is "This research made use of tools provided by Astrometry.net." The VaST software developers assume, that this statement concerns the work which uses "util/identify.sh" script from the VaST package.



Using VaST with scanned photographic plates

If you have to deal with digitized photographic materials, you'll want first to convert TIFF images (which are typically produced by scanner software) to the FITS format. It can be easily done with the tiff2fits converter. Do not forget to change your images to positive (white stars on black sky). For example:

./tiff2fits -i input.tiff output.fits
Also, you'll have to enter the information about the date and time of the observation in fits header. This can be done, among other ways, using the modhead program from the CFITSIO examples page, MissFITS or edhead from the WCSTools package. You may enter the observation date and time information in the image header by generating the usual "DATE-OBS" and "EXPTIME" header keys, or by simply putting the middle-of-exposure Julian Date into the "JD" key. You will most likely need to modify the default SExtractor settings stored in the "default.sex" file located in the VaST directory. Please use "default.sex.beta_Cas_photoplates" and "default.sex.PHOTO" as working examples (these files are also found in the VaST directory).

Say, you have digitized photographic images in "photo_data" directory. To run VaST on them, change to the VaST directory and run the program

cd vast-1.0rc64
./vast -o ../photo_data/*fit
The "-o" parameter tells VaST to use formulas (1) and (3) from Bacher et al. (2005, MNRAS, 362, 542) for magnitude calibration. This technique provide slightly better results for the aperture photometry on photographic data compared to the second-order polynome used in VaST by default for magnitude calibration. However, the standard calibration technique should also provide reasonably good results (see Figure 2 in this paper). The "-j" parameter that forces VaST to use a linear position-dependent magnitude correction (i.e. stars on one side of the image bing systematically fainter than on the other side) might also be useful for photographic plates photometry.

An example photographic dataset is available here. Beware, it's about 1G in size!

You may find some more details in the ArXiv:1403.5334 e-print "A search for new variable stars using digitized Moscow collection plates".



Search for transients with VaST

Apart from the standard "variable star search mode", where a long series of images is processed and lightcurves of detected stars are explored using the sigma-magnitude plot, VaST can be also used in the specialized "transient detection mode". In this mode VaST will process a series of four images: two first-epoch (reference) images and two second-epoch images. VaST will generate an HTML report containing a list of candidate transients. The transients are defined as either objects that were not visible on the reference images, or where at least 1 mag. fainter compared to the second-epoch images. Two first-epoch images are needed because image artifacts and star blending may cause VaST to miss a star on a single reference image, so it will appear as a false transient search mode is available. If there are two reference images - chances that the program will fail to detect a star at both of them is greatly reduced. Also note that two different reference images are needed: it would be impossible to "cheat" the program by feeding the same image to it twice.

An example dataset that allows one to test the transient search mode is available here.

The unpacked archive will contain two sub-directories with reference and second-epoch images. The search should be conducted in two steps:

# Process images with VaST
./vast -x99 -ukf ../transient_detection_test_Ceres/reference_images/* ../transient_detection_test_Ceres/second_epoch_images/*
# Run script that will generate an HTML report
util/transients/search_for_transients_single_field.sh
Be prepared - the script will ask you to download a few catalogs needed for its work, including Tycho-2, the catalogs are more about 200M in size. The transient search report will be placed in transient_report/index.html that should be opened with your favorite web browser. The report will contain a few false candidates and some good ones including asteroids and variable stars.

Known limitations:

  • The transient detection capability is still in the testing stage and is FAR FROM PERFECT, sorry...
  • You'll need a reasonably high-speed Internet connection with unlimited traffic to efficiently use the transient-detection capability. An effort is made to reduce the Internet traffic to the necessary minimum. However, at the first start, the program will need to download ~200M of catalog data. During the routine work, the program will need to transmit a few 100K of data for every processed image (necessary for astrometric image calibration using the external server). The Internet connection is also needed to access external web-databases that would allow you to check the detected transient candidates.
  • There are two transient-detection scripts for your to consider:
    util/transients/search_for_transients_single_field.sh is the simplified one that searches for transients in a single field.
    util/transients/transient_fatory_test30.sh is a more complex one, that is actually used to process NMW survey data. These scripts cannot cover all possible situations and should serve an example and inspiration for you to write your own script appropriate for your setup.
  • Image field of view should be sufficiently large to allow automatic plate solution with Astrometry.net software. The default value is 180 arcmin, if your field of view is smaller - you should edit the transient detection script util/transients/search_for_transients_single_field.sh .
  • The magnitude calibration is based on V magnitudes of Tycho-2 stars. If this is not appropriate for your system, please contact me and I'll try to develop an alternative calibration strategy for your setup.
  • Reference images should be two different images obtained during one night.
  • There are two files controlling the star-detection behavior of SExtractor: default.sex and default.conv . You may refer to SExtractor documentation for a detailed description of these files. You may find a few examples of default.sex and default.conv files in the VaST directory. The default files are meant to work for a wide variety of CCD images, however they may not provide an optimal star detection efficiency for a particular instrument. The two files fine-tuned for the "transient_detection_test_Ceres" dataset are default.sex.telephoto_lens and default.conv.telephoto_lens . To use them instead of default files, just copy these files:
    cp default.sex.telephoto_lens default.sex
    cp default.conv.telephoto_lens default.conv
    You may want to edit these file to match your own setup.


Some switches that you may use with VaST

"-9" — use DS9 instead of VaST's own viewer pgfv to view FITS files.
"-n" — do NOT perform magnitude calibration. Useless for variable star search but good for doing differential photometry with util/differential_photometry.sh script.
"-u" — always assume UTC time system, don't perform conversion to TT.
"-k" — force VaST to ignore the "JD" keyword in FITS headers.
"-x2" — accept stars with non-zero SExtractor flag: 2 - blended stars, 4 - saturated stars, 99 - accept everything.
"-e" — failsafe mode: only stars detected on the reference frame will be processed.
"-p" — tell VaST that it deals with a linear detector. This flag is useful for well calibrated CCD images, but for some CCD images it is better not to use it. Test what works best for your particular dataset!
"-o" — tell VaST that it deals with a digitized photographic plate. The magnitude calibration between frames will be done using the relation proposed by Bacher et al. (2005, MNRAS, 362, 542).
"-l" — perform sigma-filtering of lightcurves.
"-r" — assume that images are not rotated with respect to each other by more than 3 degrees.
To get the full list of the available command line arguments run:
./vast -h

Description of output files produced by VaST

After processing an image series, VaST will create a number of files in its working directory that may be useful for a future work or problem debugging.
  • Each "outNNNNN.dat" file contains an individual lightcurve of a star numbered NNNNN. This is a simple ASCII file that may be viewed in a text editor. The format is the following:
    - 1st column - JD(TT) (default) or JD(UTC) (if VaST was started with "-u" flag)
    - 2nd column - magnitude (with respect to the background level on the reference image if an absolute calibration was not done yet)
    - 3rd column - estimated magnitude error
    - 4th column - X position of the star on the current frame (in pixels)
    - 5th column - Y position of the star on the current frame (in pixels)
    - 6th column - diameter of the circular aperture used to measure the current frame (in pixels)
    - 7th column - file path corresponding to the current frame
    The extra columns specific to VaST may be easily removed as follows
    util/cute_lc out00183.dat > out00183_JD_mag_err.dat
    the output file out00183_JD_mag_err.dat will contain only three columns "JD", "mag" and "err". By default, util/cute_lc prints its output to stdout. If no lightcurve file name is provided as a command line argument, util/cute_lc will expect the input lightcurve to be sent to its stdin. You may easily change the number of digits returned by util/cute_lc by editing its source code file src/cute_lc.c and recompiling VaST (make).
  • "data.m_sigma" file contains the information used to produce the sigma-magnitude plot. It has the following format:
    - 1st column - mean magnitude of a star
    - 2nd column - estimated sigma (standard deviation) of its lightcurve
    - 3rd column - X position of the star on the reference frame (in pixels)
    - 4th column - Y position of the star on the reference frame (in pixels)
    - 5th column - outNNNNN.dat file containing the lightcurve of this star
  • "vast_summary.log" file summarizes the processing results. Its format is rather self-explanatory:
    Images processed 91
    Images used for photometry 91
    Ref. image: 2453192.38950 05.07.2004 21:18:19 ../sample_data/f_72-001r.fit
    First image: 2453192.38950 05.07.2004 21:18:19 ../sample_data/f_72-001r.fit
    Last image: 2453219.49141 01.08.2004 23:45:04 ../sample_data/f_72-091r.fit
    JD time system (TT/UTC/UNKNOWN): TT
    Transient candidates found: 34
    Number of SysRem iterations: 0
    Computation time: 14 seconds
    SExtractor parameter file: default.sex
    Total objects detected: 510
    Objects passed selection criteria: 174
    Measurements per detected object (mean, median, min, max): 34.2 16.0 2 91
    Measurements per selected object (mean, median, min, max): 78.3 84.0 40 91
    Average stars detected per image: 210.989
    Average stars matched: 203.89 (96.6354 %)
    Memory usage VmPeak: 745564 kB
    Software: VaST 1.0rc64 compiled with gcc (Gentoo 4.7.2-r1 p1.5, pie-0.5.5) 4.7.2
    SExtractor version 2.8.6 (2012-11-23)
    Processing completed on Sat Apr 13 07:04:41 UTC 2013
    Note however that the "Transient candidates found" line should be ignored in most cases. At this moment, transient detection is supported in the special four-image transient detection mode described above.
  • "vast_image_details.log" file contains information about processing of individual images:
    exp_start= 05.07.2004 21:18:19 exp= 180 JD= 2453192.38950 ap= 7.2 rotation= 0.000 *detected= 334 *matched= 334 status=OK ../sample_data/f_72-001r.fit
    exp_start= 05.07.2004 21:21:30 exp= 180 JD= 2453192.39172 ap= 7.1 rotation= -0.106 *detected= 329 *matched= 310 status=OK ../sample_data/f_72-002r.fit
    exp_start= 05.07.2004 21:24:41 exp= 180 JD= 2453192.39393 ap= 7.0 rotation= -0.157 *detected= 337 *matched= 315 status=OK ../sample_data/f_72-003r.fit
    exp_start= 05.07.2004 21:27:52 exp= 180 JD= 2453192.39614 ap= 6.9 rotation= -0.020 *detected= 345 *matched= 330 status=OK ../sample_data/f_72-004r.fit
    exp_start= 06.07.2004 20:24:42 exp= 180 JD= 2453193.35227 ap= 6.2 rotation= -0.021 *detected= 416 *matched= 321 status=OK ../sample_data/f_72-005r.fit
    ...
    If an image could not be processed, this will be indicated by "status=ERROR".
  • "vast_command_line.log" contains the command line with which VaST was started, so the exact processing parameters can be always figured out.
  • "vast_sigma_selection_curve.log" contains the "sigma-selection curve" displayed on the sigma-magnitude plot.
  • "vast_stars_with_large_sigma.log" contains the list of stars that are above the "sigma-selection curve" on the sigma-magnitude plot. The file format is identical to the one of "data.m_sigma" file. The stars listed in "vast_stars_with_large_sigma.log" have larger-than-average scatter of their lightcurves and may be investigated further, e.g., with period-search software.
  • "vast_magnitude_calibration_details_log" is a directory containing details of the frame-to-frame magnitude calibration process. The details may be viewed as follows:
    cd vast_magnitude_calibration_details_log
    for i in *.calib ;do ../lib/fit_mag_calib "$i" "$i"_param ;done
    This is useful mostly for debugging purposes.
  • "image*.cat" files are the raw SExtractor catalogs. Their format is defined in the "default.param" file (see SExtractor documentation). The correspondence between the catalogs and input images is given in the "vast_images_catalogs.log" file. These catalogs are useful mostly for debugging purposes.
  • "image*.cat.aperture" files contain the aperture diameter (in pixels) used to produce a given SExtractor catalog.
  • "vast_memory_usage.log" contains information about VaST usage of RAM.
  • "vast_list_of_all_stars.log" contains pixel coordinates of all setected stars in the reference frame of the first (reference) image. Both stars actually detected on the first frame and the ones detected only on other frames are listed.
  • "vast_list_of_all_stars.ds9" is the same as "vast_list_of_all_stars.log" except it is formatted as a DS9 region file (to be loaded into the DS9 FITS image viewer).


List of publications which make use of VaST

If you are aware of a publication which is not listed here, please, drop us a line to kirx[at]scan.sai.msu.ru so we can include it in the list!
  1. Kirill Sokolovsky, Sergei Antipin, Daria Kolesnikova, Alexandr Lebedev, Nikolai Samus, Lyudmila Sat, Alexandra Zubareva; "A search for new variable stars using digitized Moscow collection plates"
    in proceedings of the AstroPlate workshop, Prague, Villa Lanna, March 18-21, 2014 Available here.
  2. E. G. Lapukhin, S. A. Veselkov, A. M. Zubareva; "New Variable Stars in Lacerta: Area of 2.3x2.3 deg, Centered at aplha=22h50m, delta=52d00' (2000.0)"
    PZP, vol. 13, N 12 (2013) Available here.
  3. Kirill Sokolovsky, Stanislav Korotkiy, Alexandr Lebedev; "The New Milky Way: a wide-field survey of optical transients near the Galactic plane"
    in Stella Novae: Future and Past Decades, P. A. Woudt & V. A. R. M. Ribeiro (eds), ASPCS. Available here.
  4. E. G. Lapukhin, S. A. Veselkov, D. A. Yatmanov, A. M. Zubareva; "New Variable Stars in Lyra: Area of 2.3x2.3 deg., Centered at alpha=19h25m.0, delta=42d47' (2000.0)"
    PZP, vol. 13, N 4 (2013) Available here.
  5. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New Variable Stars in Auriga III"
    PZP, vol. 13, N 2 (2013) Available here.
  6. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New Variable Stars in Aquila II"
    PZP, vol. 12, N 21 (2012) Available here.
  7. E. G. Lapukhin, S. A. Veselkov, S. V. Antipin, N. N. Samus; "New Variable Stars in Auriga: Area of 2.3x2.3 deg., Centered at alpha=06h00m, delta=29d15'";
    PZP, vol. 12, N 19 (2012) Available here.
  8. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New Variable Stars in Ophiuchus III"
    PZP, vol. 12, N 17 (2012) Available here.
  9. V. Solovyov, A. Samokhvalov, B. Satovskiy; "A Possible New FU Ori-type Variable Star"
    PZP, vol. 12, N 16 (2012) Available here.
  10. V. Solovyov, A. Samokhvalov, B. Satovskiy; "New Variable Stars in Ophiuchus II"
    PZP, vol. 12, N 15 (2012) Available here.
  11. K. V. Sokolovsky, D. Gareeva, E. Gorbovskoy, A. Kuznetsov, V. Yurkov, E. Sinyakov; "New Semiregular Variable Star in Draco"
    PZP, vol. 12, N 14 (2012) Available here.
  12. S. V. Antipin, A. M. Zubareva; "New Cepheid in Cygnus and Four New Eclipsing Variables"
    PZP, vol. 12, N 13 (2012) Available here.
  13. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New UV-type Variable Star USNO-A2.0 0900-17250765"
    PZP, vol. 12, N 12 (2012) Available here.
  14. E. G. Lapukhin, S. A. Veselkov, S. V. Antipin, N. N. Samus; "New Variable Stars in Ursa Major: Area of 9.22.3, Centered at alpha=13h38m, delta=53d30'"
    PZP, vol. 12, N 10 (2012) Available here.
  15. A. C. Gupta et al. "Multiwavelength intraday variability of the BL Lacertae S5 0716+714"
    2012, MNRAS, 425, 1357 Available here.
  16. K. V. Sokolovsky; "The Variability Type and Period of V348 Aql"
    PZP, vol. 11, N 33 (17.11.2011) Available here.
  17. V. Solovyov, A. Samokhvalov, B. Satovskiy; "New Variable Stars in the Field of V458 Vul"
    PZP, vol. 11, N 31 (14.11.2011) Available here.
  18. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New Variable Stars in the Field of V496 Aur"
    PZP, vol. 11, N 28 (20.07.2011) Available here.
  19. K. V. Sokolovsky, F. D'Ammando, S. Cutini, and J. M. Gelbord; "Swift observations of BL Lacertae"
    2011 ATel #3377 Available here, also see the monitoring results page.
  20. V. Solovyov, A. Samokhvalov, B. Satovskiy; "USNO-A2.0 1425-04252279: a New Eclipsing RS CVn Star with Spot Activity of Both Components"
    PZP, vol. 11, N 21 (23.05.2011) Available here.
  21. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New Variable Stars in the Field of the Globular Cluster NGC5466"
    PZP, vol. 11, N 20 (11.05.2011) Available here.
  22. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New Variable Stars in the Field of V651 Oph"
    PZP, vol. 11, N 16 (22.04.2011) Available here.
  23. V. Solovyov, A. Samokhvalov, B. Satovskiy; "New Variable Stars in Perseus"
    PZP, vol. 11, N 14 (7.04.2011) Available here.
  24. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New Variable Stars in the Field of V2335 Oph"
    PZP, vol. 11, N 13 (7.04.2011) Available here.
  25. N. Virnina, S. V. Antipin, A. M. Zubareva; "Four New Eclipsing Variable Stars"
    PZP, vol. 11, N 9 (14.03.2011) Available here.
  26. T. Kryachko, A. Samokhvalov, S. A. Korotkiy, D. G. Lambas; "New Variable Stars in Two Fields in the Southern Hemisphere"
    PZP, vol. 11, N 8 (11.03.2011) Available here.
  27. Daniel J. Majaess, David G. Turner, David J. Lane, Tom Krajci; "Deep Infrared ZAMS Fits to Benchmark Open Clusters Hosting delta Scuti Stars"
    2011 JAVSO, 39, 219 Available here.
  28. Natalia A. Virnina; ""Tsessevich" Project: an Attempt to Find the System YY Dra. I"
    2011 OEJV, 133, 1 Available here.
  29. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New Variable Stars in Auriga II"
    PZP, vol. 11, N 4 (28.01.2011)Available here.
  30. V. Solovyov, A. Samokhvalov, B. Satovskiy; "USNO-A2.0 1425-04279615 and USNO-A2.0 1425-04280420: Two New Short-Period Eclipsing RS CVn Variables"
    2011 IBVS #5961 Available here.
  31. T. Krajci, K. Sokolovsky, A. Henden; "griz photometry of 3C 454.3 following its extreme gamma-ray flare"
    2010 ATel #3047 Available here, and see the monitoring results page.
  32. D. M. Kolesnikova, L. A. Sat, K. V. Sokolovsky, S. V. Antipin, A. A. Belinskii, N. N. Samus'; "New variable stars on digitized Moscow collection plates. The field of 66 Ophiuchi"
    2010, ARep, 54, 1000 The abstract is available here.
  33. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New Variable Stars in Aquila"
    PZP, vol. 10, N 25 (26.10.2010) Available here.
  34. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New Variable Stars in the Field of V585 Lyr"
    PZP, vol. 10, N 24 (26.10.2010) Available here.
  35. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New Variable Stars in Taurus"
    PZP, vol. 10, N 17 (18.05.2010) Available here.
  36. K. Sokolovsky, C. Maceroni, M. Hareter, C. Damiani, L. Balaguer-Nunez, I. Ribas; "A new eclipsing binary system with a pulsating component detected by CoRoT"
    2010 CoAst, 161, 59 Available here.
  37. T. Kryachko, A. Samokhvalov, B. Satovskiy, D. Denisenko; "New Variable Stars in Cygnus II"
    PZP, vol. 10, N 10 (9.03.2010) Available here.
  38. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New Variable Stars in Auriga"
    PZP, vol. 10, N 3 (2.02.2010) Available here.
  39. T. Kryachko, A. Samokhvalov, B. Satovskiy, D. Denisenko; "New Variable Stars in Cygnus"
    PZP, vol. 10, N 2 (27.01.2010) Available here.
  40. T. Kryachko, A. Samokhvalov, B. Satovskiy; "The New UV-type Variable Star USNO-B1.0 1243-0454679"
    PZP, vol. 9, N 33 (22.12.2009) Available here.
  41. K. V. Sokolovsky; "NSVS 304708 is a High Amplitude Delta Scuti Star"
    PZP, vol. 9, N 30 (5.11.2009) Available here.
  42. T. Kryachko, A. Samokhvalov, S. A. Korotkiy; "New Variable Stars in the Field of Omicron Andromedae"
    PZP, vol. 9, N 29 (5.11.2009) Available here.
  43. Alex Golovin, Kirill Sokolovsky, Natalia Virnina, Javier Lopez Santiago; "Three New Variable Stars in Indus";
    2009 OEJV, 111, 1 Available here.
  44. T. Kryachko, A. Samokhvalov, D. Denisenko, B. Satovskiy; "New Variable Stars in the Field of GRB 080605"
    PZP, vol. 9, N 24 (23.09.2009) Available here.
  45. S. V. Antipin, A. M. Zubareva, D. Kolesnikova, N. N. Samus, L. A. Sat, K. V. Sokolovsky; "CCD Observations of Four Stars Suspected in Variability from Digitized Moscow Plates"
    PZP, vol. 9, N 21 (19.06.2009) Available here.
  46. K. V. Sokolovsky, L. Elenin, N. Virnina; "New Variable Stars Discovered Using the Tzec Maun Observatory Telescopes II"
    PZP, vol. 9, N 20 (19.06.2009) Available here.
  47. T. Kryachko, A. Samokhvalov, S. A. Korotkiy; "New Eclipsing Variable Stars in Canis Minor"
    PZP, vol. 9, N 18 (17.06.2009) Available here.
  48. T. Kryachko, A. Samokhvalov, D. Denisenko, B. Satovskiy; "New Variable Stars in Gemini"
    PZP, vol. 9, N 10 (28.04.2009) Available here.
  49. K. V. Sokolovsky; "Three New Eclipsing Binaries Near the Galactic Center"
    PZP, vol. 9, N 9 (11.03.2009) Available here.
  50. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New variable stars in Andromeda II"
    PZP, vol. 9, N 7 (13.02.2009) Available here.
  51. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New variable stars in the field of SGR0501+4516"
    PZP, vol. 9, N 4 (11.02.2009) Available here.
  52. T. Kryachko, A. Samokhvalov, D. Denisenko, B. Satovskiy; "New UV-type Variable Star USNO-A2.0 1350-05226717"
    PZP, vol. 9, N 1 (3.02.2009) Available here.
  53. T. Kryachko, A. Samokhvalov, S. A. Korotkiy; "New Variable Stars in Andromeda"
    PZP, vol. 8, N 48 (8.12.2008) Available here.
  54. T. Kryachko, A. Samokhvalov, D. Denisenko, B. Satovskiy; "New Variable Stars in Ophiuchus"
    PZP, vol. 8, N 43 (24.11.2008) Available here.
  55. K. V. Sokolovsky, L. Elenin; "New Variable Stars Discovered Using the Tzec Maun Observatory Telescopes"
    PZP, vol. 8, N 42 (20.11.2008) Available here.
  56. Kolesnikova, D. M.; Sat, L. A.; Sokolovsky, K. V.; Antipin, S. V.; Samus, N. N.; "New Variable Stars on Digitized Moscow Collection Plates. Field 66 Ophiuchi (Northern Half)"
    2008, AcA, 58, 279 Available here.
  57. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New Variable Stars in the Field of Tau Aurigae"
    PZP, vol. 8, N 29 (15.09.2008) Available here.
  58. T. Kryachko, A. Samokhvalov, B. Satovskiy; "New EW Variable Star GSC 0584-01373"
    PZP, vol. 8, N 28 (15.09.2008) Available here.
  59. T. Kryachko, A. Samokhvalov, B. Satovskiy, A. V. Khruslov; "Variable Stars in the Field of GSC 4550-01669"
    PZP, vol. 8, N 27 (27.06.2008) Available here.
  60. T. Kryachko, A. Samokhvalov, B. Satovskiy, A. V. Khruslov; "Variable Stars in the Field of GSC 4329-01772"
    PZP, vol. 8, N 26 (26.06.2008) Available here.
  61. T. Kryachko, K. V. Sokolovsky, D. Denisenko, B. Satovskiy; "Low-Amplitude Eclipsing Binary Star GSC 04372-00066"
    PZP, vol. 8, N 22 (22.05.2008) Available here.
  62. T. Kryachko, K. V. Sokolovsky, D. Denisenko, B. Satovskiy; "New Eclipsing Binary Star GSC 04372-00577"
    PZP, vol. 8, N 20 (13.05.2008) Available here.
  63. T. Kryachko, K. Sokolovsky, B. Satovskiy; "Five New Variable Stars"
    PZP, vol. 8, N 8 (2008) Available here.
  64. K. V. Sokolovsky, D. O. Chekhovich, S. A. Korotkiy; "GSC 4232-02059 - a New Beta Lyrae System"
    PZP, vol. 8, N 2 (2008) Available here.
  65. S. V. Antipin, D. Kolesnikova, L. A. Sat, K. V. Sokolovsky, S. A. Korotkiy; "A New High Amplitude Delta Scuti Star on the Scanned Moscow Archive Plates"
    PZ, vol. 27, N 8 (22.11.2007) Available here.
  66. K. V. Sokolovsky, D. O. Chekhovich, S. A. Korotkiy; "GSC 4232-02515 - a New Eclipsing Binary Star"
    PZP, vol. 7, N 26 (24.10.2007) Available here.
  67. D. M. Kolesnikova, K. V. Sokolovsky, S. V. Antipin, N. N. Samus; "Moscow Digital Variables. III"
    PZP, vol. 7, N 24 (19.10.2007) Available here.
  68. D. M. Kolesnikova, K. V. Sokolovsky, N. N. Samus, S. V. Antipin; "Moscow Digital Variables. II"
    PZP, vol. 7, N 3 (5.02.2007) Available here.
  69. A. L. Manannikov, K. V. Sokolovsky, N. N. Samus, S. V. Antipin; "Moscow Digital Variables. I"
    PZP, vol. 6, N 34 (22.12.2006) Available here.
  70. K. V. Sokolovsky, E. P. Pavlenko; "USNO-B1.0 1381-0460341: a New Eclipsing Binary System Near V1500 Cyg"
    PZP, vol. 6, N 33 (5.12.2006) Available here.
  71. K. V. Sokolovsky, S. V. Antipin, S. A. Korotkiy; "Period Changes in the Algol-type Eclipsing Binary System TYC 1744 2329 1"
    PZ, vol. 26, N 7 (20.10.2006) Available here.
  72. K. V. Sokolovsky; "Optical Variability of the Seyfert Galaxy FBQS J161047.7+330337"
    PZP, vol. 6, N 18 (30.06.2006) Available here.
  73. K. V. Sokolovsky, V. R. Amirkhanyan; "USNO-B1.0 1323-0548678: a New EW Star in the Field of BL Lac"
    PZP, vol. 6, N 1 (27.01.2006) Available here.
  74. S. V. Antipin, K. V. Sokolovsky, A. A. Lebedev; "GSC 02050-00745: A New RR Lyrae Star with Blazhko Effect"
    IBVS 5654 (2005) Available here.
  75. K. V. Sokolovsky, A. A. Lebedev; "POISK - a SExtractor front-end for search of variable objects in series of CCD images"
    12th Young Scientists' Conference on Astronomy and Space Physics, held in Kyiv, Ukraine, April 19-23, 2005, p. 79 Available here.

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