How to create an ID Card for an object not (yet) present in the AAVSO VSX?


Occasionally, you may want to perform photometry on a target star that is not yet present in the AAVSO VSX database. In this example, we will use a FITS image of ASASSN-24fq, a variable star detected by the ASAS-SN1 sky survey at position RA = 22h 16m 20.71s, Dec : +21° 40' 01.90" (J2000.0). At the time of image acquisition, ASASSN-24fq was not yet listed in the AAVSO VSX database (it meanwhile is). We obtained about 100 images of ASASSN-24fq and wanted to perform photometry on this star. We first needed to create an ID Card for it.


To begin, we followed the steps in the Variable ID Card menu using the New command:


    • Enter the target star's name in the Name field.
    • Click the AAVSO Lookup button to search for the star in the VSX database.

In the case of ASASSN-24fq, because it wasn't yet listed in the AAVSO VSX, Phoranso displayed the message "Target star not found on AAVSO VSP website. Looking up variable in SIMBAD." Upon pressing OK, Phoranso also failed to retrieve information from SIMBAD, indicating that the star was unavailable in both databases at that time.



Correct steps to follow


  1. Select the New command from the Variable ID Card menu to display an empty New Variable ID Card window

  2. In the Name field, enter the target star name: ASASSN-24fq  

  3. In the RA field, enter the RA of the target star: 22 16 20.71 

  4. In the Dec field, enter the Dec of the target star, +21 40 01.90  

  5. Click the AAVSO chart ID field. This will expand the New Variable ID Card window, revealing the Select reference image section

  6. Here you can select a DSS image, FITS image or AAVSO chart. Choose FITS image and select the previously mentioned FITS image of ASASSN-24fq

  7. Phoranso will solve the image and retrieve catalog data for all stars present. Your Variable ID Card window should now resemble the example below, where Phoranso successfully identified the new variable star near a bright star.



From this point, continue by selecting the Reference, Check and Comparison stars as described in the New command.


(1) The ASAS-SN Sky Patrol (All-Sky Automated Survey for Supernovae) is an automated program to search for supernovae and other astronomical transients, headed by astronomers from Ohio State University (US). It has a series of robotic telescopes in both the northern and southern hemispheres and surveys the entire sky approximately once every day.