In the Gen2 Status catalog eric gave a link to in an earlier ticket, I see STATL.DEC_OFFSET and STATL.RA_OFFSET. Do these describe user-specified offsets?

cloomis, Gen2 status values simply make available the coordinates received from the telescope (TCS) in various formats.  The FITS.SBR versions of these are formatted to the sexigesimal format typically used in FITS headers.  Because tracking and guiding both continuously correct the telescope, these values fluctuate in small increments or decrements about the commanded position.  It sounds like what you want is to detect tracking or guiding, with the appropriate dome open status, and then check the commanded position, which does not change until the telescope is commanded to a different coordinate.

The status values for the last command position are FITS.SBR.RA_CMD and FITS.SBR.DEC_CMD

As regards the offsets, I will double-check on this, but I believe even if the telescope is commanded by an offset, the commanded values will change to reflect the offsets and so will the instantaneous RA/DEC values.

BTW, this is extremely easy to check on the telescope if we have 10 minutes of free time, even if the dome is closed.  Since we are often waiting for darkness with HSC, should be no problem to arrange a quick test.

Two question:

• Offset cards. I do not see any offsets listed in the FITS. section of the Gen2 Status keys, not do I see any in the NAOJ page at https://docs.google.com/spreadsheets/d/e/2PACX-1vSI1K1BQL58iTBCwDmeYGWQZDWrTqyuxLL-pvMpF1G9D0wy53cG6qzPZ7tKqyvaFx2O1bxMIiAGVmSa/pubhtml?gid=1323981495&single=true . I could easily have missed something. And I do not see any offset cards in HSC headers.

Is there actually a standard we should follow, or should we record user offsets as internal W_ cards?

• RA_CMD vs. RA: do you know what the components of the differences between them are? One can guess at some of them, but it would be nice to know,....

@cloomis, sorry but I am completely missing the point here. What offsets are you talking about? Dither positions?

Mainly any user-applied offsets, like what would be applied by the HSC "SetupField ... OFFSET_RA ..." commands.

I think you will find that the RA/DEC recorded in the HSC FITS files is with the offset applied.  If the offsets are noted within the instrument-specific keywords, I am not aware of it.  The offsets are given in the phase 2 queue files though.  Probably should have someone from the HSC instrument team answer this definitively though.  Surely, @rhl should know the answer to this WRT HSC files?...

Given that it is in the FITS.SBR namespace, I take it it would be acceptable to add RA_CMD and DEC_CMD to the header cards?

I am inclined to do that, as well as to add W_RAOFF and W_DECOFF just to make those explicit and accessible for those few times we really care.

Noted that we should ask HSC team.

Added RA_CMD, W_RAOFF etc

ics_gen2Actor merged at 44dc1bf, tagged 1.4.7
ics_actorkeys merged at 7b0d890, tagged 1.4.10

This was a total lie: we do not have real info from Gen2