evtool failing when trying to merge event files

[b291c571]

Hello,

I am trying to merge event files using the evtool command and it is failing. I am getting the following feedback from the command:

evtool: 2.29.2.3 eSASS4DR1 Dec 08 14:50:53 2023
evtool/evtool_main: **WARNING1** GTI filtering not yet done on file 1
evtool/evtool_main: **WARNING1** GTI filtering not yet done on file 2
evtool/evtool_main: **WARNING1** GTI filtering not yet done on file 3
evtool/evtool_main: **WARNING1** GTI filtering not yet done on file 4
evtool/evtool_main: **WARNING1** GTI filtering not yet done on file 5
evtool/evtool_main: **WARNING1** GTI filtering not yet done on file 6
evtool/evtool_main: **WARNING1** GTI filtering not yet done on file 7
evtool/evtool_main: memset==.false., so memory setting for large files is used.
evtool/evtool_main: Merging infiles.
evtool/evtool_main: Merging headers.
evtool/evtool_main: Update filter settings.
evtool/evtool_main: Merging extensions.
evtool/merge_extensions: Merging 7 files.
evtool/merge_extensions: Infiles will be read 1 extension at a time.
evtool/getColNumsForReading_tBinTable: **STOP** Column X: specified data type is D but file has J
evtool: FAILED

I am not sure how to change the data type for it to run the correct way. I have downloaded the event files from the catalogue search on the eROSITA website. Has this problem happened before and is there a way to fix this issue?

Best,
Brandon Coleman

[MiriamRamos]

Hi Brandon,

It seems you are trying to merge "source event lists", i.e., the event lists that come in a given source package. However, as explained here:

https://erosita.mpe.mpg.de/dr1/eSASS4DR ... b_Point_84 ,

those files miss critical information from the input event files (e.g., bad pixels and attitude) and therefore cannot be used for further analysis in evtool or srctool.

You need to download the event list of the sky tile where your source lies so that you can continue with your processing.

Best wishes,
Miriam

[b291c571]

Hello Miriam,

Thank you for the information on this topic. I do see where the source products come from the sky tile itself. When looking at the sky tile for the source in question I go to download the events file and There is only one EventList Fits file. Is that the way it's supposed to be? What is the point of the evtool if there is only one fits file for the event list? I apologize if I seem ignorant in this situation.

Best,
Brandon

[MiriamRamos]

Hello Brandon,

evtool cannot only merge event lists, which is what I believe you wanted to do. But there are scientists who do not want to use the event list that we provide, since it has information from the 7 eROSITA telescopes. Some people might want to use only a subset of telescopes, create images, extract regions, etc.

The EventList FITS file covers a large area (3.6x3.6 deg), I guess you want to explore only a small region, around your source of interest(?). So, evtool can help you to extract only that part of the sky to create an image, for example.

Best wishes,
Miriam

[b291c571]

Hello Miriam,

I guess I just don't understand what evtool does. I thought the point was to be able to merge multiple event files into a single image. Are you stating that I just need to put the single event list as the input file and manipulate the commands to have it centered on the coordinates I want?

Best,
Brandon Coleman

[JeremySanders]

Hi Brandon

It's not very clear what you want to do. Can you explain what you want to achieve from the start? Why do you need to have an event file centred on a source? Is it for making images or source extraction?

If your source covers multiple tiles, you'll need evtool to merge them. If you want to recentre an event file about a position, then you can use radec2xy, but that may not be necessary.

Cheers

Jeremy

[b291c571]

Hey Jeremy,

I am just trying to understand how to get from an event list to a source to then extract a spectra, light curve, etc. I just want to understand the process of eSASS so I can look at the spectra of a specific source.

I looked up the source on the eROSITA database and found the data products for the source in question and I originally thought that reading the tool cookbook on 'evtool' I needed to take the 7 event files included in the source data tar file and merge them together to make an image of that source. Then Miriam told me that evtool cannot do that from the source data, that I need to download the event list for the skytile that my source falls in. That event list is a singular fits file. I did run 'radec2xy' on that file, but it didn't seem to do anything from there. My guess is that I do not need to run radec2xy on that file as it already has the 'X' and 'Y' headers in the file.

At this point do I even need to run 'evtool' or do I just proceed with other commands to get to where I need to go?

Best,
Brandon Coleman

[JeremySanders]

Hi Brandon

All radec2xy does is recalculate the X and Y coordinates to be centred on that position in the event file. By default, it should be the centre of the sky tile.

If you'd like to make an image from the event file, then evtool is what you should use. It's a bit easier to use radec2xy to set the X and Y coordinates first, as by default as the evtool center_position is zero by default.

If you want to extract source products (spectra, lightcurves, responses), then srctool can be run on the standard event file. evtool is not needed to be run, unless you want to filter first for time, flags, telescope modules, pattern, etc, or want to merge sky tiles.

Cheers

Jeremy