Frequently Asked Questions
- May/should I use survey data in my submissions?
You can not only discover new variable stars by data-mining the publicly available survey data, you can also combine survey observations with
yours when you find new objects with your own data.
Using those observations spanning several months or years, you will be able to improve the elements for your star. And when you only have a
few observations, they may even allow you to classify it and solve it without the need of your own follow-up.
The easiest way to look for survey data is to use the external links in the VSX star page (for new objects, you can also do it after a positional search).
Because of security issues ASAS-SN epoch photometry is not available through the external links.
- Should the magnitudes from surveys be taken at face value?
NO. The different surveys have different resolution, this means that nearby stars will affect the photometry differently depending on
the survey, you have to check VizieR for the presence of companions in order to perform a correction if needed.
This is a table showing the approximate distances in arcseconds where a companion will be included in the survey photometric aperture.
For bright stars contamination may reach longer distances:
You can get a spreadsheet to correct for light contamination upon request.
A remark should be added to indicate if a correction was applied (recommended) or not and to provide information about the identification,
magnitude and distance of the companions.
E.g.: "ASAS-3 magnitudes contaminated by GSC 00000-00000 (V= 14.5; sep. 17"). Range has been corrected."
- Should I add a reference when I submit a discovery or a revision based on data-mining results?
Yes. Always add the survey reference when you use their data. Also the star identifier(s) in that survey should be added to the Other names field.
Some complete references of the most widely used surveys with their proper formats are:
|Reference name:||Pojmanski, G., 2002, The All Sky Automated Survey|
|Reference name:||Henden, A. A.; et al., 2016, AAVSO Photometric All Sky Survey (APASS) DR9 |
|Reference name:||Wozniak, P. R.; et al., 2004, Northern Sky Variability Survey: Public Data Release|
|Reference name:||Drake, A. J.; et al., 2009, Catalina Real-time Transient Survey|
|Reference name:||Butters, O. W.; et al., 2010, The first WASP public data release|
|Reference name:||Kochanek, C. S.; et al., 2017, The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0|
|Reference name:||Howell, S. B.; et al., 2014, The K2 Mission: Characterization and Early Results|
PHOTOMETRY AND PASSBANDS
- Where do I get magnitudes for my comparison stars?
Most of the new objects will not have sequences available through VSP so here are
If the star is brighter than V= 10.5 (and fainter than 7th mag., for bright stars you should use the GCPD or HIPPARCOS) and South of +28º,
you'll have a V-mag. from ASAS-3
(and you'll be able to combine ASAS-3 data with yours the same way as you are doing with the data from other surveys, like NSVS data for
For stars fainter than V= 10.0 (it saturates at brighter magnitudes) you have APASS V magnitudes. They are available through VizieR.
If there are no APASS or ASAS-3 data, you can get a V magnitude from UCAC3 (UCAC4 has zero point issues) and CMC15 using 2MASS colors.
Note that UCAC3 is not a default VizieR catalog. Get both the f and a magnitudes (choose the faintest result you get) and enter
the UCAC4 position.
For fainter stars, IPHAS,
SDSS can also be used to get good V magnitudes
(also Rc magnitudes). Remember that transformed values
are not as accurate as measures taken with the original passband filters but can be used when nothing else is available.
You can get a transformation spreadsheet upon request.
- What passband should I use for my report?
There are several options regarding passbands. It depends on your set-up.
Are you observing with filters (V?, Rc?, Ic?) or unfiltered (clear)?
If you use filters you have to choose comparison stars with magnitudes measured on the corresponding filter and give a range.
If you are going unfiltered, you can give a mean magnitude (e.g. V or Rc from APASS) from a catalogue as the maximum value and an amplitude
based on your observations with the passband "clear" and the "Minimum is an amplitude" box marked as the minimum value.
If you are using comparison stars to get your ranges, depending on the passband of those magnitudes, your ranges should be CR (R mags. used
for the comparison stars) or CV (V mags. used for the comparison stars). Most CCDs have an R-like response so CR is usually the one to be
"clear" is not a passband per se so it should not be used in the maximum magnitude field.
- How should I determine the magnitude range of a variable?
Scatter should always be taken into account. Do not include outliers in the determination. Derive mean magnitudes both for the maximum
and minimum fields. In the case of strictly periodic variables without mean magnitude changes, get mean magnitudes from the phase plot.
In the case of objects with mean magnitude and amplitude changes between cycles (SR, M, RS, etc.), derive a mean magnitude for the brightest
and faintest recorded cycles.
REMARKS AND COMMENTS
- What should I include in the remarks field?
The remarks field is meant to include additional information on the star or the photometry.
- NO URLs or references of any kind should be written there. They belong to the Reference fields.
- NO information that could be included in the main table should be written here as a remark.
E.g.: "The correct position is..." --> If an improved position is found, it should replace the current one in the main table.
Use the revision form to modify parameters included in the main table.
- What is the revision comment meant for?
That field is used to list all the changes made in a revision with the corresponding sources used to make those changes.
E.g.: "Type, period, epoch and range from ASAS-3 data. UCAC4 position."
In the case of new stars, that field is meant to list additional sources used to modify some parameters in the submission that are not
included in the reference given or are not derived from the observer's own data analysis.
E.g.: "Mean magnitude from APASS. PPMXL position."
- May I leave some of the submission form fields blank?
- You have to provide as much information as possible.
- You always have to upload supporting documentation (e.g.: a phase plot for periodic variables and a JD light curve for irregular objects) or a reference if the star was formally published.
- You should always provide a magnitude range or a mean magnitude and an amplitude.
- You should always specify the passband of your observations.
- You always have to classify the variable (check the Variability types document for more information). If the classification is not confirmed, mark the uncertainty box.
- DO NOT mark the uncertainty box for empty fields. E.g.: if there is no period given, there is no uncertainty.
- DO NOT fill in fields that are not relevant to your submission. E.g.: if your object is not a nova, do not write a year in the "Outburst (nova) year" field.
- Is it acceptable to submit an object with only one night of data and without any classification?
Nowadays the number of variable stars have increased exponentially. If you find a new variable star, we recommend that you dedicate at least
the minimum time/effort required to classify it and determine its elements (for periodic variables).
There may be exceptions, like a single flare detected in a red dwarf (spectroscopic or multicolor archival data can be used to confirm its
classification) or a single eclipse in an EA-type that cannot be confirmed with follow-up or survey observations.
- What should I provide as supporting documentation?
- A phase plot is required for periodic variables.
- A JD light curve should be uploaded for irregular variables.
- A finding chart should be provided for objects in crowded fields especially if they are not included in astrometric catalogues or do not
have reliable cross-identifications.
- What should the phase plot look like?
It is a good idea to display more than one variability cycle in phase plots so the light curve shape can be clearly seen.
Phase 0 in the phase plot should be the epoch given in the table.
- Display phase 0 to 2 in the case of pulsating variables so the maximum is displayed in the middle.
- Display phases -0.25 to 1.25 (or -0.5 to 1.5) in the case of eclipsing binaries so the secondary eclipse is displayed in the middle.
Remember that an epoch of maximum has to be given in the case of most pulsating variables (with the exception of RV Tauri stars and SR
variables displaying LSP (Long Secondary Periods)) and hot-spotted stars and an epoch of minimum has to be given in the case of eclipsing
binaries, ellipsoidal variables and dark-spotted stars.
- Can I copy the star identifiers from VizieR and paste them to the Other names field?
Be careful with formats. SIMBAD lists identifiers with the proper formats but
it is not complete.
VizieR will include all data and identifiers for your object but sometimes catalogue acronyms will be in the column header and not in the
information field so you need to be careful.
The VSX New Star form and the VSX guidelines have examples of correct formats.
Check formats in the Dictionary of Nomenclature of Celestial Objects.
- Always add a J before the positional part of the J2000.0 coordinate-based identifiers (e.g. 2MASS J23171981+3102538, not 2MASS 23171981+3102538).
- GSC identifiers use leading zeroes but Tycho identifiers do not (e.g. GSC 01800-02202; TYC 1800-2202-1).
- What cross-identifiers should I write in the Other names field?
It depends on the star's brightness. Bright stars will have lots of names because they will be included in old classical catalogues like HR,
HD, SAO, BD, CD, CPD, PPM, HIP, TYC, GSC, etc.
Faint stars will only have identifiers from more recent and deeper surveys like 2MASS, UCAC4, GSC2.3, USNO-B1.0, IPHAS, SDSS, CMC15, etc.
It does not make sense to give GSC2.3 or CMC15 identifiers for a 5th magnitude star that already has all the bright star names because those
IDs won't ever be used to identify it.
- How can I request an AUID to submit my data?
Use the Request AUID link in the AAVSO UID field if you need to submit data for a star without an AUID. We get a notification and assign the
AUID immediately. If we do not encourage observations of that object (e.g. constant stars, stars with extremely low amplitudes), you will
be contacted. This is the fastest way to get an AUID assigned. E-mails to HQ may take several days to be acted upon.
- Should I request AUIDs for every variable in my field of view?
No. Please do not submit AUID requests for stars with extremely low amplitudes (e.g. Kepler microvariables). All those variables are in VSX
but we do not encourage observations from the ground for them because the required photometric precision cannot be reached.