Release Date: July 27, 2011
This is one of two ASCII formats that the AAVSO accepts for uploading a file of variable star observations. Please use the WebObs File Upload page  to upload your file in the AAVSO Extended Format. The other format , which is intended for visual observers, is called the AAVSO Visual File Format .
Visit the Software that exports to AAVSO format  page to help format your observations.
The extended format has two components: parameters and data. Each component is discussed in detail below.
The format is not case sensitive.
The Parameters are specified at the top of the file and are used to describe the data that follows. Parameters must begin with a pound sign (#) at the start of the line. There are six specific parameters that we require to exist at the top of the file. Personal comments may also be added as long as they follow a pound sign (#). These comments will be ignored by the software and not loaded into the database. However, they will be retained when the complete file is stored in the AAVSO permanent archives.
The six parameters that we require are:
The six parameters explained:
The OBSCODE and DATE parameters may also be included elsewhere in the data. Our data processing software will read these parameters and will expect all following data to adhere to them. (For example, you can add "#OBSCODE=TST01" to the report and all subsequent observations will be attributed to observer TST01.)
If you want to put a blank line between your parameter records and your data records, be sure to comment the line out with the pound sign (#). WebObs will not accept a file with blank lines that are not commented out.
After the parameters comes the actual variable star observations. There should be one observation per line and the fields should be separated by the same character that is defined in the DELIM parameter field. If you do not have data for one of the optional fields, you must put "na" as a place holder. The list of fields are:
#TYPE=EXTENDED #OBSCODE=TST01 #SOFTWARE=IRAF 12.4 #DELIM=, #DATE=JD SS CYG,2450702.1234,11.135,0.003,V,NO,STD,105,na,na,na,na,na,070613,This is a test
#TYPE=EXTENDED #OBSCODE=TST01 #SOFTWARE=GCX 2.0 #DELIM=, #DATE=JD #OBSTYPE=CCD #NAME,DATE,MAG,MERR,FILT,TRANS,MTYPE,CNAME,CMAG,KNAME,KMAG,AMASS,GROUP,CHART,NOTES SS CYG,2450702.1234,11.235,0.003,B,NO,STD,105,10.593,110,11.090,1.561,1,070613,na SS CYG,2450702.1254,11.135,0.003,V,NO,STD,105,10.594,110,10.994,1.563,1,070613,na SS CYG,2450702.1274,11.035,0.003,R,NO,STD,105,10.594,110,10.896,1.564,1,070613,na SS CYG,2450702.1294,10.935,0.003,I,NO,STD,105,10.592,110,10.793,1.567,1,070613,na
Note the existence of the #NAME,DATE... line in the above format. Since it is prepended with a #, it will be ignored by our software. Feel free to do this if it makes writing and reading the format easier for you.
Ensemble photometry is permitted under this format. You need to pick one star (the check star) in addition to the target to be measured by the technique. The check star should not be included in the comparison-star ensemble. This star's calculated magnitude should be put in the KMAG field, so that if the true magnitude of the check star is found to be different at a later date, a simple zeropoint offset can be added to your ensemble value. If ensemble is used, CNAME should be set to ENSEMBLE and CMAG should be set to "na", as shown below.
#TYPE=EXTENDED #OBSCODE=TST01 #SOFTWARE=GCX 2.0 #DELIM=, #DATE=JD #NAME,DATE,MAG,MERR,FILT,TRANS,MTYPE,CNAME,CMAG,KNAME,KMAG,AMASS,GROUP,CHART,NOTES SS CYG,2450702.1234,11.235,0.003,B,NO,STD,ENSEMBLE,na,105,10.593,1.561,1,070613,na SS CYG,2450702.1254,11.135,0.003,V,NO,STD,ENSEMBLE,na,105,10.492,1.563,1,070613,na SS CYG,2450702.1274,11.035,0.003,R,NO,STD,ENSEMBLE,na,105,10.398,1.564,1,070613,na SS CYG,2450702.1294,10.935,0.003,I,NO,STD,ENSEMBLE,na,105,10.295,1.567,1,070613,na SS CYG,2450702.2234,11.244,0.003,B,NO,STD,ENSEMBLE,na,105,10.590,1.661,2,070613,na SS CYG,2450702.2254,11.166,0.003,V,NO,STD,ENSEMBLE,na,105,10.497,1.663,2,070613,na SS CYG,2450702.2274,11.030,0.003,R,NO,STD,ENSEMBLE,na,105,10.402,1.664,2,070613,na SS CYG,2450702.2294,10.927,0.003,I,NO,STD,ENSEMBLE,na,105,10.292,1.667,2,070613,na
This means your ensemble solution gave 11.235, 11.135, 11.035 and 10.935 for the B,V,Rc, and Ic (respectively) magnitudes of SS Cyg for the first group, and 11.244, 11.116, 11.030 and 10.927 for the second group. Your ensemble solution also gave 10.593, 10.492, 10.398, and 10.295 for the BVRcIc magnitudes of the check star for the first group.
Differential photometry is permitted under this format. CNAME should be the name of the comparison star (chart label, GSC number, etc.), CMAG should be its instrumental magnitude, KNAME should be the name of the check star and KMAG should be the instrumental magnitude of the check star. In this manner, HQ can calculate (K-C) to determine a time-series error, and HQ can also adjust the MAG field if at some later date the true standard magnitude of the comparison star becomes known. We highly recommend that you use "STD" (standardized ) instead of DIF (differential) as your data will not appear on the light curve generator, nor be properly validated otherwise. Here is an example of the differential format:
#TYPE=EXTENDED #OBSCODE=TST01 #SOFTWARE=GCX 2.0 #DELIM=, #DATE=JD #NAME,DATE,MAG,MERR,FILT,TRANS,MTYPE,CNAME,CMAG,KNAME,KMAG,AMASS,GROUP,CHART,NOTES SS CYG,2450702.1234,1.065,0.003,B,NO,DIF,105,10.170,110,11.090,1.561,1,070613,na SS CYG,2450702.1254,1.114,0.003,V,NO,DIF,105,10.021,110,10.994,1.563,1,070613,na SS CYG,2450702.1274,1.001,0.003,R,NO,DIF,105,10.034,110,10.896,1.564,1,070613,na SS CYG,2450702.1294,.988,0.003,I,NO,DIF,105,9.947,110,10.793,1.567,1,070613,na