Interacting with FITS windows


Let's acquaint ourselves with the Phoranso FITS windows by opening one of the downloaded science FITS images. Follow these steps:


    1. Go to the File menu.
    2. Choose Open FITS File
    3. Navigate to the Documents directory on your PC and then proceed to the Phoranso folder.
    4. Inside the Phoranso folder, locate the Tutorials subfolder.
    5. Within the Tutorials subfolder, navigate to the folder named FS CMi 20230329, which houses the Sciences folder containing 104 FITS images.
    6. Select one of the files from the Sciences folder.
    7. Click the Open button to initiate the process


Consider selecting the file FS CMi_533275_West_Clear_45s_-19d.fit. The FITS window will subsequently appear as follows:



To gain proficiency with the user interface controls located at the bottom of the window, we highly recommend reading this section. Ensure that you understand how to manually solve the image and load catalog information. Both of these steps are essential prerequisites before progressing to the next stage. Execute both steps. Your image should now resemble:




Creating ID Cards for variable stars in your FITS window


Photometry of Science images necessitates the identification of the target variable star, along with one or more reference stars, one check star, and potentially zero or more comparison stars. Throughout this User Guide, we will commonly refer to the reference, check, and comparison stars as calibration stars. For each selected calibration star, it is essential to provide information about their magnitudes in various color bands, among other details.


To streamline this process, Phoranso employs an intelligent Variable Star Database, allowing you to input information about your target star and calibration stars just once. Phoranso memorizes this information for future use in what we term an ID Card. This functionality eliminates the need for repetitive data entry, ensuring consistency in your comparison stars even over extended periods of time. The Variable Star Database contains a dedicated ID Card for every Target star you intend to measure in your Science images. 


Follow the steps from this chapter to create an ID Card for FS CMi. But replace the example "V0844 Her" with "FS CMi" in the Target Star Identification section. Subsequently, proceed with the steps outlined in the Reference, Check, and Comparison Stars Identification from a FITS Reference Image section. In this process, choose one Reference star, one Check star and one Comparison star in the image:

    • Designate the star with the AAVSO label 12.6 as the Reference star
    • Designate the star with the AAVSO label 12.8 as the Check star 
    • Designate the star with the AAVSO label 13.6 as the Comparison star


After making these selections, click the Save ID Card button. Your image should display as follows:




Creating ID Cards for other variable stars in your field of view


You will notice the presence of other variables in your FITS window, indicated by white circles and name labels. ZTF J073811.78+055010.8 is one such example. Let's explore how to create ID Cards for some of these variables. 


Click the Clone ID Card button to open the corresponding tabular window, displaying all known variable stars (from the AAVSO VSX database) present in your FITS window. For each star, name, J2000.0 coordinates, variability type, magnitude range, and period are provided. 



Some variables, such as ASAS J073643+0611.0 and ASAS J073810+0614.2 are notably bright, and due to the likelihood of saturation, we won't generate ID Cards for them. However, the other four are eclipsing variables with a favourable magnitude and large enough amplitude. We decide to create ID Cards for these four entries. To do so, select them in the table and click Save ID Cards. 


This action results in the addition of four new ID Cards to the Variable Star Database, all sharing the same Reference, Check and Comparison stars as FS CMi. Further details can be found in the section Creating ID Cards for other variable stars in your field of view in this chapter.


Checking if AAVSO AUIDs exist for the created ID Cards


At the end of this tutorial, we will generate AAVSO reports for FS CMi and the four additional variables  identified. When submitting reports to the AAVSO International Database (AID), it's important that each variable is designated by its unique AUID (AAVSO Unique Identifier). Let's verify the existence of AUIDs for our five entries.


Navigate to the Variable ID Card menu and select ID Cards matching FOV. This displays a tabular window presenting the ID Cards of the five variable stars within the field of view (FOV) of your FITS image.



Check the column AUID to ensure that AUIDs exist for each variable. If they do, no further action is necessary. In the event of missing AUIDs, this section explains the process of requesting an AUID using Phoranso.




Proceed to step 4 of the tutorial.