American Association of Variable Star Observers (AAVSO)
Sun, 12/17/2023 - 18:21

    I enconter problem/ error message with Vphot analysis.
    I participate to SNEWS program, I reveived the first images from BSM_NM2, I began analysis for doing two color tranform (V & I) (after doing the sequence) and I encounter errror message :
    Server Error in '/app' Application.
    Index -1 is either negative or above rows count.
    Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

    Exception Details: System.IndexOutOfRangeException: Index -1 is either negative or above rows count.

    Source Error:
    An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
    Stack Trace:
    [IndexOutOfRangeException: Index -1 is either negative or above rows count.]
       System.Data.DataView.GetRow(Int32 index) +1893578
       Restricted_ColorPhotReport.CreateReport(Int32 seqID, Double Tbr, Double Tb, Double Tr, Int32 ap, Int32 minSNR, Int32 searchRad, Single initFWHM, Int16 filterBlue, Int16 filterRed, Int64 imgID_B, Int64 imgID_R, Double factor, Boolean useFactor, Hashtable compsToExclude) +3504
       Restricted_ColorPhotReport.Page_Load1(Object sender, EventArgs e) +821
       System.Web.UI.Control.OnLoad(EventArgs e) +97
       System.Web.UI.Control.LoadRecursive() +61
       System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +693

    It happend for the two target.
    I checked that the telecope set up contain parameter for I & V filters.

    Do you know what happend ? Could you help me ?

best regrds


American Association of Variable Star Observers (AAVSO)
TV Gem SNEWS target: advice on how to assess

Greetings Eric,

First peek at the images is always exciting!
My suggestions:
- The FOV is 88x59 arcmin  (
       The recommended chart from the gsheet is 11 deg wide! There are only 3 comps in the FOV.
       You can show the APASS data and make a selection from them, building up a good ensemble.
       Or you can go to the SequenceTeam to make the selection for you.(
     The goal is you want a solid VPhot sequence selection that others who measure TV Gem can use.
- You've selected all the VSX comp stars in the field. Don't bother with those below SNR 100
- The V image is a 4.2s exposure with snr of 465 and max adu of 11k. Request exposure adjustment to 10s
    Check the exposure level for I also
    You will be working with comps dimmer than the target, so increase the exposure as much as possible so that the snr of the comps is improved.
- Request 3 exposures each of V and I; In TransformApplier you can aggregate the 3 measurements (ie, no need to stack)
- The fault shows that you were using the Two-Color Transform tool; Use the TransformApplier tool instead.
      I believe the fault was caused by inadequate comps: they were too close to the edge.
- Do this analysis for your other SNEWS star to reduce our workload on modifying the exposure specs.
   Send a change request to We will put these in about once a week.