Variable Star Discovery Policy

Nowdays, there are many sources of variable star lists. Some of them contains objects that are not present in the other ones. And not all lists include information about publication date, which makes it difficult to prepare a complete list of discoveries, co-discoveries, independent discoveries and non-discoveries.

"Discovery is not done by discovery. You find many different things. None of them are discovery until you understand what it is."

The search for variable stars started in 2017 by exploring the neighbourhood of stars hosting an exoplanet transit. More than a hundred of variables were submitted to the Variable Star Index individually using own photometry data combined with survey ones (eg. ASAS-SN Sky Patrol or SuperWASP). A few months later the search changed to data mining using survey data. Because in all cases (dubious variables are never submitted unless there was some kind of a manual error) the photometric data is enough to classify variables, unpublished (missed in catalogs) objects are submitted without any additional observations. This is planned in the last stage, after publication of the paper about MGAB catalog of variable stars.

  • Variability flags marked as 'true', 'yes', '1' etc. based on RMS are not treated as discoveries and none of these confirm if is indeed variable and contains a bunch of false positives. All MGAB stars are checked manually by eye (even on single images, if needed) to make sure variables are indeed real.

  • Objects with a general classification by spectroscopy/survey magnitudes are not treated as discoveries. Example: Young Stellar Object (YSO) from SIMBAD based only on IR-excess or H-alpha emission isn't enough to claim if the discovery, as photometric variability was not mentioned.

  • Variable stars from the ATLAS catalog are treated a discoveries only when are not marked as 'dubious'. Submitted variable stars after the publication date to arXiv with non-dubious code will have their main name & discoverer changed in the VSX database. This is applied to all variable stars except MGAB-V266 (an independent discovery), because of:

    • Deep eclipses by ATLAS were not mentioned (marked as a pulsator (PULSE) with a doubled period)

    • We are already observing eclipses of this system extensively for a future publication

  • All variables previously submitted to the VSX by others are excluded. This also applies to new group of stars, where objects were primarily unknown during the cross-match, but were added to the VSX independently before they are published on this page.

  • Gaia DR2 variables are all excluded even if their classification is incorrect (eg. DSCT_SXPHE for cataclysmic variables or MIRA for Young Stellar Objects).

  • RR Lyrae candidates from Pan-STARRS1 are all treated as independent discoveries and both names will be always shown in the VSX. A confirmed part of objects was previously accepted to the Variable Star Index and the rest are treated as candidates. High amplitude variables (with impossible values for RR Lyrae stars) are included with a low RRAB/RRC probability, meaning the machine learning wasn't fully effective or/and the threshold was too low. The search for variables was never based on this catalog.

  • ZTF variable star candidates from the "A catalog of over ten million variable source candidates in ZTF data release 1" paper are also not treated as discoveries for stars that have been submitted after the publication date. The full discovery credit will be given only to those stars which are validated (dwarf novae and listed short period variables with plotted graphs), as mentioned by authors of the paper. An independent discovery will be considered when the full table will become available in VizieR. A large set of randomly selected stars will be taken for validation to estimate the amount of false positives.

  • The official ZTF lists (alerce.online & lasair.roe.ac.uk) will not be considered as discoveries unless they are published in other catalogs mentioned above. The discovery date given on sites is the first ever positive detection of the target, not a variability discovery report (eg. MGAB-V301, which has a TNS report by the ZTF more a day later and more than a year before in VSX, so the credit was corrected). Because the paper of ZTF variables is still in development, those sites are treated as experimental before the ZTF's catalog is fully released. So far, variability types are mostly correctly given, so it's worth looking for the paper in the future.

  • Not all authors of papers submit their findings to SIMBAD, VizieR or even VSX. If a variable star with a reasonable variability explaination in a previously published paper will be found after the submission with MGAB as a main name, it will be corrected.

  • A proper credit from using datapoints coming from a certain survey in plots is given.


Discovery dates for all objects:

  • MGAB-V1 to MGAB-V300 - based on submission date to the VSX, except objects from the paper "The discovery of eleven nova-like VY Scl type stars" (Murawski, G.; 2019). Three first objects (MGAB-V195, MGAB-V196 and MGAB-V197) were submitted individually to the VSX in January 2019, but the rest (from V201 to V208) were put to the paper and sent to The Astronomical Reports journal with submission date of 7th February, 2019. The journal had several internal problems, which caused delays and it was finally published on 16th January, 2020. Objects with designations from V201 to V208 were submitted to the VSX earlier (in August 2019) to avoid further problems about the discovery credit. This is explained because of the nova eruption of MGAB-V207, which happened in July 2020, which caught attention. This object was mentioned as a RR Lyrae candidate in the paper "Identification of RR Lyrae stars in multiband, sparsely-sampled data from the Dark Energy Survey using template fitting and Random Forest classification" (Stringer, K. M.; et al., 2019) with a submission date of 1st May, 2019. Because of an earlier submission date (by almost 3 months), object marked as a candidate with an improper classification and late submission to VizieR (in August 2019 the catalog was not present in VizieR to investigate the discovery credit), the variability discovery credit is kept.

  • MGAB-V301 to MGAB-V550 - 25.09.2019

  • MGAB-V551 to MGAB-V1120 - 15.10.2019

  • MGAB-V1121 to MGAB-V1146 - 11.01.2020

  • MGAB-V1147 - MGAB-V1290 - 27.01.2020

  • MGAB-V1291 - MGAB-V3361 - 21.02.2020

  • MGAB-V3362 - MGAB-V3370 - 15.05.2020

  • MGAB-V3371 - MGAB-V3774 - 20.12.2020 (except MGAB-V3390, MGAB-V3395, MGAB-V3396 - individual submissions to the VSX)


Clarification on discovery, co-discovery, independent discovery counts:

  • Full discovery - the variability was not confirmed anywhere and the report is the first.

  • Co-discovery - the submission to the VSX is done with a group of people and is the first that confirms the variability.

  • Independent discovery - RR Lyrae candidates from Pan-STARRS1, which by usual are correctly identified as variable, but failed to apply a proper classification. If the submission via MGAB catalog was done with a group of people (like a co-discovery), but the target is present in the catalog of RR Lyrae candidates, is also treated as an independent discovery. This is also given if a specified star from the MGAB catalog is the main star topic in a new paper and authors explain that the target was observed for a long time. Additionally, it is applied to MGAB-V266 for reasons explained above.

  • Total discovery count - is a sum of full discoveries, co-discoveries and independent discoveries.