[PIPE2D-1022] Plan for flux calibration test of May-June 2022 runs Created: 13/Apr/22  Updated: 04/Nov/22  Resolved: 15/Jul/22

Status: Done
Project: DRP 2-D Pipeline
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Task Priority: Normal
Reporter: Takuji Yamashita Assignee: Takuji Yamashita
Resolution: Done Votes: 0
Labels: EngRun, flux-calibration
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Attachments: PNG File skydist_may.png    
Issue Links:
Relates
relates to PIPE2D-1075 Standard stars for September 2022 eng... Done
relates to PIPE2D-1108 Standard stars for November 2022 engi... Done
Sprint: PreEngRun06June, preEngRun07Sep
Reviewers: hassan

 Description   

Make a plan and make a sample list for the flux calibration test during the commissioning runs in May-June 2022. This ticket is to summarize the discussion we had and to specify the plan for the flux calibration test.

Target stars

Because the 2D DRP uses F-type stars as flux standards, we desire an observation of F-type stars in the commissioning runs. The objects to be observed should have reliable spectra but such objects are generally much bright. After discussion on/offline with the DRP team and Moritani-san, the sample now includes a star from CALSPEC and some of the GA target stars. The stars are brighter than ~10 mag, which requires a short exposure of ~10 sec (estimated from the fact that 12 mag stars are saturated in 60-sec exposures according to ETC). We choose GA stars with X-shooter spectra because its wavelength coverage entirely covers PFS.

Candidates for May run

  • CALSPEC star: BD+29 2091 (G = 10 mag, RA = 11 h, the first half of the night)
  • GA target stars: 34 F-type stars with X-shooter spectra (G = 6-10 mag, RA = 10-22 h, the second half of the night)

Exposure and fibers

In the online talk, Moritani-san agreed that we will have short-exposure observations for the flux calibration test. Our observations cannot share fibers with the distortion test which exposes in 60 sec.

F-type stars, which were selected with broad-band photometry by Ishigaki-san, will be included in FLUXSTD fibers from the targetDB. This observation chance will allow us to check the F-type selection.

We require, at least, 1 object during the commissioning runs.

 

 Comments   
Comment by Takuji Yamashita [ 13/Apr/22 ]

I am sorry. I accidentally made this ticket in OBSPROC. I will delete it.  Moved to PIPE2D.

Comment by Takuji Yamashita [ 13/Apr/22 ]

G mag vs. Teff, and RA-Dec plot of the GA target stars with X-shooter.

Comment by Takuji Yamashita [ 13/Apr/22 ]

Magnitude distribution of F-type star candidates is in https://pfspipe.ipmu.jp/jira/browse/PIPE2D-982

Comment by Takuji Yamashita [ 13/Apr/22 ]

We also need the broad-band photometry set whose filters are similar to ones of HSC, not only Gaia photometry. These bright stars are saturated in SDSS and PS1. APASS DR10 catalog is available for this purpose. The saturation limit is at 7 mag.

Comment by Takuji Yamashita [ 13/Apr/22 ]

Moritani-san pointed out the effect on short-exposures images by the opening and closing shutter. It takes 0.4 seconds to complete opening and closing the shutter, respectively. This movement causes a different effective exposure time across an image. Although we do not know how large this effect is, we need to consider this effect in our short-exposure observation (~10 seconds).
A flat frame with the same short exposure will help us correct this effect. A signal-to-noise ratio of such a short-exposure flat itself becomes low. We may be able to correct this effect if we can fit the short-exposure flat with a function and use it to correct an object frame flat-fielding-calibrated with a long-exposure flat frame.

This topic was discussed online with NAOJ and IPMU today. 

Comment by Takuji Yamashita [ 18/May/22 ]

I limit the GA target stars to 16 stars which are F-stars, are brighter than 7 mag, and have APASS DR10 photometry data with griz bands. Among of them, the 6 highest-priority stars have small photometry errors of < 0.2 mag and small Gaia ruwe of < 1.4.

Comment by hassan [ 14/Jul/22 ]

Takuji Yamashita: can we close this ticket now that the June Eng Run is finished?

Comment by Takuji Yamashita [ 15/Jul/22 ]

Yes, we can close this ticket. Thanks. 

Comment by Takuji Yamashita [ 08/Sep/22 ]

For the September Eng Run, I made a new target list of standard stars. These targets will be used for the raster scan test but the data can also be used for the flux calibration test. The list contains 6 DA white dwarfs selected from Narayan et al. (2019) which are 18-20 mag stars, and 2 F-stars from CalSpec which are 9 mag and 16 mag stars. I sent the list to Moritani-san. I have no order of priority from a point of view of flux calibration. 

Their coordinate information was fetched from Gaia DR3 and the photometries were from PS1 DR2 or APASS DR10. 

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