AAVSO: American Association of Variable Star Observers

AAVSO Exoplanet WebObs Users Guide
Revision 1.0

I. Introduction
The following are instructions on how to upload an exoplanet observation to the AAVSO Exoplanet Database using the Exoplanet Database WebObs page.
The following related documents are available at http://astrodennis.com.
1. "A Practical Guide to Exoplanet Observing"
2. "User Guide: AstroImageJ Macro for Creating an AAVSO Exoplanet Report"

II. Exoplanet Database WebObs Page
The main web page used to upload exoplanet data can be found here. It is necessary for the user to have first logged in to the main AAVSO web site with the user's AAVSO username and password in order to use the Exoplanet WebObs page.

An example of the Exoplanet WebObs page is seen in Figure 1 below.

Figure 1. Sample WebObs Page

User entries on the WebObs page consist of:
1. The user's site and equipment profiles associated with this observation. These profiles can be defined using the following web page: Site & Equipment. The instructions that follow assume that such profiles have been defined.
2. The location of one or more images, associated with this observation, that are to be uploaded to the database. As a minimum, one image should be uploaded showing a plate solved star field that includes the target star and the final set of comparison stars that were part of the exoplanet observation. Such images can be in any common picture format.

Figure 2 is an example of such an image:

Figure 2. Sample Comparison Star Image

3. An ASCII file that represents the "report" of the exoplanet observation should then be uploaded. The next section contains a description of the data elements and valid ranges for each of the data elements in such a report.

III. Exoplanet Report
The exoplanet report format has two components: parameters and data, where the latter represents a series of measurements taken during the time of the observation. Appendix A contains a sample report. Each component of the report file is discussed in detail below.

A. Parameters

The Parameters are specified at the top of the file and are used to describe the measurement data that follows. Parameters must begin with a pound sign (#) at the start of the line. There are a number of specific parameters that are required at the top of the file. Personal comments may also be added as long as they follow a pound sign (#). These miscellaneous comments will be ignored by the WebObs software and not loaded into the database. However, they will be retained when the complete file is stored in the AAVSO permanent archives. The format of the parameters is case sensitive, as shown in the example in Appendix A.

*Required parameters are:

  • #TYPE= Must be EXOPLANET.
  • #OBSCODE= The official AAVSO Observer Code for the primary observer of the data submitted. Limit: 5 characters.
  • #SOFTWARE= Name and version of software used to create the observation. If it is private software, put some type of description here. For example: "#SOFTWARE=AIJ Version 3.2". Limit: 255 characters.
  • #DELIM= The delimiter used to separate the fields in the data section of the report. The allowed delimiters are: , ; | : ! / ?. You can use a tab as a delimiter, indicating that choice with the word 'tab'.
  • #DATE_TYPE= The type of time reference for the date/times used in the data section of the file. Times are midpoint of the observation. Note that data to a precision of milliseconds (i.e., 8 decimal places) is acceptable.
    Valid values are:
    • JD_UTC: Julian Day (e.g., 2454101.75634)
    • HJD_UTC: Heliocentric Julian Day
    • BJD_UTC: Barycentric Julian Day
    • BJD_TT: Barycentric Julian Day, Terrestrial Time
    • BJD_TDB: Barycentric Julian Day, Barycentric Dynamical Time.
  • #OBSTYPE= The type of equipment used to make the measurements in the data file. It can be CCD or DSLR. If you are using a CMOS camera, submit this field as CCD and note the actual camera type in the NOTES section below.
  • #STAR_NAME= Name of the host star that the exoplanet orbits. The Star must be recognized in MAST. This will include all the targets found in the various exoplanet campaigns such as Kepler, TESS, etc. Ideally this will be an AAVSO AUID or the name of a star recognized by VSX. Limit: 100 characters.
  • #EXOPLANET_NAME= The name of the exoplanet. Ideally, this should be the Star Name with a small letter suffix of 'b', 'c', 'd', etc. However, it can also be the arbitrary name of an exoplanet used in an exoplanet campaign. Limit: 100 characters.
  • #BINNING= 1x1, 2x2, 3x3, or 4x4. This is the binning used by the imaging camera.
  • #EXPOSURE_TIME= The exposure time in seconds. Limit: less than or equal to 600 seconds.
  • #FILTER= Valid AAVSO filter designation. Must be one of the 2-3 letter short names from the list of AAVSO filter designations (see Appendix B). Some exoplanet observations may also be made using a CBB (Clear Blue Blocking or so-called Exoplanet Filter). If a filter is not used, or if a clear filter is used, then the CV filter type should be used.
  • #DETREND_PARAMETERS= A comma separated list naming the detrend parameters whose data is included in the following data records. You can list 0 to 4 names here and then you must have the corresponding number of columns at the end of each row in your data records below to hold the actual detrend data for each measurement. Limit: 100 characters.
  • #MEASUREMENT_TYPE= An indication of how each measurement in the data records should be interpreted (Dmag indicates differential magnitude or Rnflux indicates relative normalized flux.

Optional parameters are:
  • #SECONDARY_OBSCODES= A comma separated list of the official AAVSO Observer Codes for any secondary observers associated with this observation. Limit: 60 characters.
  • #PRIORS= Free form field to note "priors" used for modeling this exoplanet transit - e.g., period, radius of host star, limb darkening coefficients Limit: 250 characters.
  • #RESULTS= Free form field to note the observation results, including, for example, (Rp/R*)^2, a/R*, Tc, and inclination. Limit: 250 characters.
  • #NOTES= Freeform description of this observation. This could include a description of weather conditions, systematics associated with this observation, other anomalies, image pixel deviation, etc. Limit: no limit on number of characters.


B. Data

The actual observational measurement data follows the parameters. There should be one measurement per line and the fields should be separated by the same character that is defined in the DELIM parameter field. A "na" or "n/a" should be placed in the Measurement Error or Detrend Data fields if no data exists for the respective field, although leaving the data field blank is also acceptable.

The list of data fields in each data row are:
  • Date: The date of the measurement, of the type specified in the header DATE parameter.
  • Measurement Data: The value of the differential measurement of the type specified in the header MEASUREMENT_TYPE parameter. Decimal field(15,8)
  • Measurement Error: Photometric uncertainty associated with the Measurement Data. Decimal field(12, 6). If not available, put "na", "n/a", or leave blank.
  • Detrend data_1: The first of up to four (4) detrend parameters in the same order and as many as there are in the header DETREND_PARAMETERS field. Decimal field(12, 6). If not used, put "na", "n/a", or leave blank. This also applies to the other Detrend fields below.
  • Detrend data_2: The second of up to four (4) detrend parameters.
  • Detrend data_3: The third of up to four (4) detrend parameters.
  • Detrend data_4: The fourth of up to four (4) detrend parameters.


Appendix A: Sample Exoplanet Database Report


#TYPE=EXOPLANET
#OBSCODE=CDEC
#SOFTWARE=AstroImageJ
#DELIM=,
#DATE_TYPE=BJD_TDB
#OBSTYPE=CCD
#STAR_NAME=Wasp-12
#EXOPLANET_NAME=Wasp-12b
#BINNING=2x2
#EXPOSURE_TIME=45
#FILTER=V
#DETREND_PARAMETERS=Airmass
#MEASUREMENT_TYPE=Rnflux
#SECONDARY_OBSCODES=CDEC1,CDEC2
#PRIORS=Period=1.09142,R*=1.63,u1=0.391,u2=0.3027
#RESULTS=Depth=0.0128,a/R*=3.2165.Tc=24557393.601332
#NOTES=Seeing was very good, no known systematics
# DATE DIFF-MAG MERR DETREND_1 DETREND_2 DETREND_3 DETREND_4
2457393.50269,0.515620,0.001884,1.867946,n/a,n/a,n/a
2457393.50327,0.508506,0.001858,1.859892,n/a,n/a,n/a
2457393.50384,0.508466,0.001848,1.851973,n/a,n/a,n/a
2457393.50442,0.515412,0.001864,1.844246,n/a,n/a,n/a
2457393.50500,0.512654,0.001854,1.836449,n/a,n/a,n/a
2457393.50557,0.510856,0.001856,1.828740,n/a,n/a,n/a


Appendix B: List of Standard AAVSO Filter Names


The complete reference list is available at: https://www.aavso.org/vsx/index.php?view=api.bands
Here is a short list of the more likely filters to use:
  • CV : Clear (No filter)
  • CBB: Clear Blue Blocking (sometimes referred to as 'Exoplanet' filter)
  • U : Johnson U
  • B : Johnson B
  • V : Johnson V
  • R : Cousins R
  • I : Cousins I
  • SZ : Sloan z
  • SU : Sloan u
  • SG : Sloan g
  • SR : Sloan r
  • SI : Sloan i
  • TG : Green Filter (or Tri-color green). This is commonly the 'green-channel' in a DSLR or color CCD camera.
  • TB : Blue Filter (or Tri-color blue). This is commonly the 'blue-channel' in a DSLR or color CCD camera.
  • TR : Red Filter (or Tri-color red). This is commonly the 'red-channel' in a DSLR or color CCD camera.
  • O : Other filter not listed above, must describe in Notes