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Submitting Variables to VSX

We encourage individual submission of new variables to the Variable Star Index (VSX). These can be single stars that you have discovered through your own observations or through data-mining; batches of stars, such as from a publication that is not already included in VSX; or changes/modifications/comments on existing VSX stars.

As opposed to asteroid discovery, you will get little or no credit for discovering a new variable star. It is pure science and the willingness to contribute to the community. A new variable will typically have some assigned name (from an existing catalog like GSC, 2MASS, etc.), and sometime later, it may also have an assigned GCVS name (this can take years). Your name will not be attached, except as a reference. You do not get to name your discovery. There are rare occasions when an unusual object garners attention, and an informal discoverer's name gets attached: McNeil's Object, Sakurai's Object, Barnard's Star, etc. Don't count on it, though!

Adding stars to VSX helps the community. When studying a particular star, observers typically use one or more neighboring stars as comparison stars. By letting the community know about every variable, observers can search VSX when selecting their comparison stars and know that they are not selecting a known variable. Adding variables to VSX also broadens the database of variables, giving more selection to researchers who are interested in a particular class, period, location for their studies. You may think that adding only one star is not important, but it is like voting - thousands of people adding one star apiece can be extremely important, and your particular star might be that really unusual one that everyone wants to study.

So, let's get into the details. While the discussion below is geared towards someone submitting original observations leading to the discovery of a variable, you can also do data-mining of existing catalogs like ASAS and NSVS. Just beware that there is a double standard: we are more critical of data-mined submissions because we expect the submitter to do some work, such as period analysis, rather than just regurgitating information already available from a given survey's site. Also, don't be too critical of objects already contained within VSX: we have accepted complete lists of previously published objects rather than applying criteria to each and every object on those lists. New submissions are subject to more strict quality control.

I. IS YOUR OBJECT VARIABLE?

To make it into VSX, the object must be proven variable. What constitutes proof, though? Here are some basic guidelines. We will bend the rules in unusual circumstances, but in general, if you follow these guidelines you have a very good chance of having your favorite object added to the system.

a. Variability must be determined beyond a shadow of a doubt. If you submit few datapoints, you need to justify your conclusion with supporting evidence: large variability (include measurement errors), red color/mira typing using 2MASS, etc. We strongly encourage that you observe your object often and submit a true light curve rather than a few discrepant measures. Submission of discoveries from visual observations is discouraged, except for transient objects like novae. If you are suspicious of visual variability, we recommend joining the VSX Discussion Group and asking questions or requesting confirmation.

b. Unfiltered observations are discouraged. There are many systematic problems with unfiltered observations. If you must submit unfiltered photometry, you need to check a plot of airmass for the observational dataset so that you can see if your variation mimics or mirrors the airmass change (a common problem). You should also check the color of the object and of the comparison stars, if possible (Tycho B-V, 2MASS colors, something that helps you understand the color differences). We may request more supporting evidence for unfiltered submissions. Observing with at least two filters is highly useful for discovery work—ou can often roughly classify a star if you have its color and light curve shape.

c. For transient objects, such as novae, we strongly recommend that you first submit your discovery to the IAU Central Bureau for Astronomical Telegrams. That disseminates the information the fastest, and also is the avenue for obtaining confirming observations of your object (CBAT usually contacts the AAVSO for followup observations). You can also announce your discovery on many of the alert maillists, such as vsnet-alert and baavss-alert.

II. WHAT TESTS SHOULD I PERFORM BEFORE SUBMISSION OF A DISCOVERY?

a. First, you need highly accurate coordinates of your new object. There are many software packages that can do this for you, but you should get a position with no worse than an arcsec or two of error.

b. Minor planets are the vermin of the sky. They get into many images, and when near stationary points, can be very slow moving. Check to see if one of these might be your new star at the SN Candidate Minor Planet Checker. We also highly recommend that your observations be made over several days so that you can look for even small motion.

c. Check to see if this is already a known variable. The best place to start is VSX itself. You should do an area search, as an exact coordinate match is unlikely, and some reported variables had large error in their discovery report. Other sources to search include SIMBAD and VizieR. (VizieR will also give you cross-identifications and photometry from existing catalogs, useful information to submit with your report).

d. If you are observing unfiltered, don't compare your results against any of the photographic surveys (DSS, POSS, etc.) to demonstrate "variability". Many red objects will appear brighter on your images than on the archival plates; this can often be many magnitudes of difference.

e. Look carefully at your images. There are many defects that can lead to false variability. We've already mentioned airmass effects, but there are ghost images of bright stars, scattered light, hot/cold pixels that migrate through images during time series, etc. Think of any way that a problem could effect your data and guard against it before assuming variability. If you are uncertain, ask the experts on one of the maillists we've mentioned, or aavso-photometry, etc.

III. SUBMITTING YOUR RESULTS TO VSX

a. You need accurate coordinates. Anything with more than an arcsec of error is discouraged. It is easy to get subarcsec errors with the modern astrometric reference catalogs now available. If the object appears on some common catalog, you will be asked for that cross-id. Coordinates should come from an astrometric catalog unless you know that your coordinates are better. Some common examples of cross-identifications:
  • GSC 01234-06789 (5 digits before and after the dash, use leading zeroes if necessary)
  • 2MASS J11431012-5804040 (use a J before the coordinates)
  • USNO-A2.0 0300-13671194
  • USNO-B1.0 0319-0360318 (use a dash between USNO and the catalog version, it is part of the acronym)
  • GSC2.3 S111210165373
  • UCAC4 810-003941
b. You need an estimate of the mean magnitude and of the amplitude, or of minimum and maximum magnitude. If you have calibrated reference stars in your image, use those to determine the zeropoint and the target magnitude. Use catalogs like APASS, ASAS-3 (V-filtered), CMC14 or UCAC3 (through transformations) to get V magnitudes.
You can also use USNO-A2.0, USNO-B1.0, GSC2.3, etc. if the star is too faint and not present in the other surveys, but you should indicate the type of magnitude and its source. This will likely be modified by some observer in the future, but is needed as a guideline for all observers and query tools.

c. Submit supporting evidence. At minimum, we request a plot of the photometry with time on the horizontal axis and magnitude on the vertical axis. If you have sufficient information to analyze the light curve, determining period and classifying the star, then you should also submit a phase plot. You can also include the actual data in a tabular form as it may clarify suspicious light curves or help in a better determination of type and/or period later on. Submitting the data in tabular form only will slow down the acceptance process as someone then has to plot that data. Do not submit the actual data under the assumption that this Web site will archive that data, as VSX is not the AAVSO International Database. We do not guarantee that any submitted data will be retained.

d. Most 14th magnitude stars are easily identifiable on the DSS with good coordinates. However, for crowded fields, or very faint stars, or stars that do not appear in one of the major catalogs like NOMAD, you should submit a finding chart. The rule of thumb is that if there is any chance for confusion, identify. You want people to be able to find this new variable! These finding charts should be in jpeg or gif and reasonably small; north and east marked, and some indication of scale (verbal is ok).

IV. NEW VARIABLES/SUBMISSION FROM DATA MINING

In general, the data submitted to VSX for new variables found in (public) survey data should be as complete as possible: the position, variability type, and maximum and minimum magnitude should always be given. For periodic variables also the period and epoch (time of minimum for eclipsers, and of maximum for pulsating and eruptive variables) are required.

a. Always give the id of the object from the survey, e.g. NSVS 123456 or ASAS J123456-7840.1.

b. The positions given by surveys like NSVS and ASAS3 are not very precise and may have errors of 10" and more. If it is possible to unambiguously link the object to one from an astrometric catalog, give the id from that catalog and use its position. Depending on their brightness, stars closer than 60" from each other may be blended and measure as one object in some of the surveys, try to choose the most probable identification based on colors or magnitudes.

c. Do not attach the light curves provided by the NSVS or the ASAS3 web site, nor the NSVS or ASAS3 data themselves. These are easily available from within VSX. Instead provide phase plots (for periodic variables) or combine light curves from several surveys into a single plot, making sure data from different surveys are distinguishable. When two or more synonyms are present in the NSVS database, combine these on a single plot as well, preferably also with different symbols and/or colors. Data from other surveys for which there is no link-out from VSX should be attached or an url should be provided.

d. Some general remarks on the use of data from particular surveys:
  • The date given by NSVS is MJD-50000 = JD-2450000.5. VSX expects a JD for the epoch, so add 2450000.5 to the NSVS date
  • Use flag 15636 for NSVS data
  • In general, do not use ASAS data of category D.
  • Submissions based only on Tycho photometric data are not acceptable.
V. NEW VARIABLES/SUBMISSION FROM THE LITERATURE

a. A number of variable star catalogs has been imported into VSX. However a large number of variables have been described in the literature, which have not been assigned a GCVS name and have not been incorporated into VSX. For other variables up-to-date information exists in the literature (e.g. corrections of GCVS or survey data) but it has not yet been entered into VSX. Your help to make VSX more complete and up-to-date is also welcome.

b. Provide all data found in the paper. Use the position as given the paper, or provide a better position (from an astrometric catalog) based on the id given in the paper. Information which cannot readily be placed into the standard VSX fields, should be added as a comment. E.g.: magnitude at secondary minimum for an eclipsing binary, epoch of secondary minimum for an eccentric eclipser, etc.

c. Provide the bibcode of the publication and the link to the ADS abstract page (http://adsabs.harvard.edu/abs/...) when it exists. For preprints published on astro-ph, give the url of the abstract page as well (e.g. http://arxiv.org/abs/astro-ph/0102987). When a bibcode or astro-ph entry does not exist, give the url of the online publication whenever possible. When a publication cannot be accessed online, provide a scanned copy, so that the moderators can verify your submission. Notes in email discussion groups such as vsnet-alert, AAVSO-discussion, etc. are acceptable as references when they provide enough information to decide that the object is a variable (in principle the same rules as in sections I and II are valid here).

d. If there are more than 20 or so new objects or revisions available electronically in tabular form from a single publication, mention this on vsx-dis. Often these can be more easily imported into VSX, rather than be entered manually.

VI. THE VSX PROCESS

Once you've submitted a new star for inclusion in VSX, the request is sent to a group of volunteer "moderators." These folk are experts in variable stars, usually having looked at thousands of light curves and often long-time observers themselves. One of more of the moderators will look at your submission. If you have been diligent and have submitted an obvious candidate, it will often be approved within a very short time (hours to a day or two), depending on the workload.

There will be submissions where the moderator thinks insufficient or incorrect information has been submitted. He or she will then usually contact the submitter, asking for clarification. Do not consider this as confrontation or lack of respect; these people are truly trying to help. They may offer suggestions as to how to submit later discoveries to make their process easier in the future.

Also, do not be angry or discouraged if your submission is rejected. The moderators will give you their reasoning for the rejection. Read it carefully! You will get rejection often in life, and astronomy is no different. Most professionals submit dozens of proposals during their career with the majority being rejected by their peers. Learn from the comments and try again!

At any time, the moderators may invoke their right to revise or otherwise update any submission made to VSX for clarity, consistency, or convention, whenever they believe the modification can be made without adversely affecting the integrity of the submission. Typically, you will be informed of any changes made by the moderators.

VII. OTHER LINKS

Note that these comments are geared towards submission to VSX. VSX submission does not preclude sending your data analysis to some other additional source, perhaps as a formal paper for publication. We do not retain any kind of right to your data, though we expect to publish a paper series that includes all new discoveries with their discoverer acknowledged. There are many journals that accept variable star research, and we recommend that you look at them all carefully. The ones we've found most useful are:

OEJV (http://var.astro.cz/oejv/)
A good basic journal. Electronic only. Now refereed.

Peremennye Zvezdy (http://www.astronet.ru/db/varstars/)
Run by the GCVS folks. Electronic only. Refereed. The supplement contains primarily observational results and matches most discovery projects.

IBVS (http://www.konkoly.hu/IBVS/IBVS.html)
Run by the IAU Commission 27 and 42, this is a fully refereed journal. Electronic and hardcopy. Harder to get papers published here; usually require full analysis.

JAAVSO (http://www.aavso.org/publications/jaavso/)
Run by the AAVSO; fully refereed and both electronic and hardcopy. There is a page charge for non-members.

JBAA (http://www.britastro.org/jbaa/)
Primarily for members of the BAA. Nice journal published 6 times per year. No electronic version.

PASP (http://www.journals.uchicago.edu/PASP/)
This fully refereed, professional journal will accept quality articles from amateurs. Page charges.

Many other professional journals accept variable-star articles, but the ones listed above are the most common. Good luck!