Log of LBC Twilight Sky Flats

To flat-field LBC images, twilight sky flats are needed; the enclosure is too compact and the surface too uneven to obtain useful dome flats. During each twilight period, usually only ~2 filters per side can be covered, so it is sometimes necessary to use archived flats. Flats taken within several months of the run should be fine (need a reference or check on this), so long as nothing was done to the filters or instrument that might alter the illumination pattern, e.g. a filter was cleaned. Cleaning of a lens that is far from the focal plane, like the corrector lens L1, should not affect the flats. Dates when the filters or lenses were cleaned are listed here.

Twilight sky flats can be downloaded from the LBT archive by anyone, since they are flagged as "Calibrations". Click the box next to "Add Calibration Files" and enter "SkyFlat" as the Object name to limit the search within any given range of dates.

Lists of LBC twilight sky flats, by month:

The tables below, the first for LBC-Blue and the second for LBC-Red, list the number of twilight flats with median count levels within a good (acceptable) range for each filter and each month for the last 12 months (if you need flat info that is older than this period, then please let us know). The median counts and median absolute deviation were measured within a 2048 x 2048 box on chip 2 [51:2098,1877:3924], roughly centered on the optical axis. The ~500 ADU bias level has not been subtracted. Flats with median counts between 10,000 and 30,000 ADU are considered "good", while those with median counts between 7500 and 40,000 ADU are deemed "acceptable". These ranges are somewhat arbitrary, however the "good" range is based on SNR considerations at the low end and, at the high end, it runs up to about half-well. The "acceptable" range loosens these restrictions in case only 1 or 2 "good" flats are found.

date SDT_USpec U-BESSEL B-BESSEL V-BESSEL g-SLOAN r-SLOAN
LBC-Blue
date SDT_USpec U-BESSEL B-BESSEL V-BESSEL g-SLOAN r-SLOAN
202212            
202211 8(9)          
202210 5(6)       4(8) 4(11)
202209 6(9) 3(6) 20(21) 11(13) 10(10) 20(21)
202208            
202207            
202206   9(10) 18(21)      
202205 23(32) 9(10) 18(23) 13(18) 27(31) 15(21)
202204 12(24) 15(21) 9(13)   19(23) 23(36)
202203 10(12) 25(32) 8(10) 5(6) 32(37) 5(11)
202202 8(11)   5(7) 13(17) 14(15)  
202201 2(3)   3(4) 2(3)    

date V-BESSEL R-BESSEL I-BESSEL r-SLOAN i-SLOAN z-SLOAN Y-FAN F972N20 TiO _784 CN_817
LBC-Red
date V-BESSEL R-BESSEL I-BESSEL r-SLOAN i-SLOAN z-SLOAN Y-FAN F972N20 TiO _784 CN_817
202212                    
202211   8(11)                
202210       2(7) 6(11)          
202209 9(12) 10(10) 7(11) 7(10) 10(10) 10(10) 5(7) 7(10)    
202208                    
202207                    
202206 5(10)   9(10)   7(9)          
202205 5(5) 20(26) 19(24) 15(22) 11(15) 9(10) 3(9) 1(7)    
202204 19(24)   10(15) 21(29) 22(30) 12(32)        
202203   4(6)   35(43) 11(12) 5(10) 9(13) 9(12)    
202202   20(29)   9(13)            
202201   9(10)                

Table Notes:
  • 20200228: Flats were taken in cloudy conditions.
  • 20201122: Flats were taken in cloudy conditions.
  • 20201123: Flats were taken in cloudy conditions.
  • 20210319: Ignore the beginning of night flats; dome lights were on.

How to create the table above:

The tables above are now created automatically by a background Python program. No user action is needed.

Before the Python program, the tables were created manually. The steps outlined below are for archival purposes, they are not needed now.

The following procedure was used to create the table manually above:
  1. In ~lbto/kuhn/LBCTwilightFlats lbcsky [B|R] [filter] -y YYYYMM
    1. this will create a series of *.dat files, one for each filter and camera combination.
  2. copy files over to my laptop (/Users/olga/LBC/SkyFlats/LBCTwilightFlats)
  3. run grepsed.scr to grep all of the *dat files in that directory and output to a file (like "newsum.txt")
  4. run createtab.py on newsum.txt to create the table that can be copied and pasted into the Twiki above.
  5. attach all non-null *.dat files to this Twiki page.

-- %USERSIG{OlgaKuhn - 2018-05-31}%

Comments

 
I Attachment Action Size Date Who Comment
createtab.py.txttxt createtab.py.txt manage 4 K 25 Aug 2018 - 19:04 OlgaKuhn grepsed.scr and createtab.py work on output files from lbcsky cam fil -y yyyymm
grepsed.scrscr grepsed.scr manage 86 bytes 25 Aug 2018 - 19:04 OlgaKuhn grepsed.scr and createtab.py work on output files from lbcsky cam fil -y yyyymm
sf_B_B-BESSEL_202201.datdat sf_B_B-BESSEL_202201.dat manage 561 bytes 27 Jan 2022 - 17:31 YangZhang  
sf_B_B-BESSEL_202202.datdat sf_B_B-BESSEL_202202.dat manage 745 bytes 02 Mar 2022 - 17:33 YangZhang  
sf_B_B-BESSEL_202203.datdat sf_B_B-BESSEL_202203.dat manage 918 bytes 27 Mar 2022 - 17:39 YangZhang  
sf_B_B-BESSEL_202204.datdat sf_B_B-BESSEL_202204.dat manage 1 K 04 May 2022 - 19:55 YangZhang  
sf_B_B-BESSEL_202205.datdat sf_B_B-BESSEL_202205.dat manage 1 K 06 Jun 2022 - 18:18 YangZhang  
sf_B_B-BESSEL_202206.datdat sf_B_B-BESSEL_202206.dat manage 1 K 06 Jun 2022 - 18:18 YangZhang  
sf_B_B-BESSEL_202209.datdat sf_B_B-BESSEL_202209.dat manage 1 K 07 Sep 2022 - 23:59 YangZhang  
sf_B_SDT_Uspec_202201.datdat sf_B_SDT_Uspec_202201.dat manage 504 bytes 27 Jan 2022 - 17:31 YangZhang  
sf_B_SDT_Uspec_202202.datdat sf_B_SDT_Uspec_202202.dat manage 988 bytes 02 Mar 2022 - 17:33 YangZhang  
sf_B_SDT_Uspec_202203.datdat sf_B_SDT_Uspec_202203.dat manage 1 K 27 Mar 2022 - 17:39 YangZhang  
sf_B_SDT_Uspec_202204.datdat sf_B_SDT_Uspec_202204.dat manage 1 K 04 May 2022 - 19:54 YangZhang  
sf_B_SDT_Uspec_202205.datdat sf_B_SDT_Uspec_202205.dat manage 2 K 06 Jun 2022 - 18:18 YangZhang  
sf_B_SDT_Uspec_202209.datdat sf_B_SDT_Uspec_202209.dat manage 869 bytes 06 Sep 2022 - 20:43 YangZhang  
sf_B_SDT_Uspec_202210.datdat sf_B_SDT_Uspec_202210.dat manage 678 bytes 16 Nov 2022 - 17:34 YangZhang  
sf_B_SDT_Uspec_202211.datdat sf_B_SDT_Uspec_202211.dat manage 865 bytes 16 Nov 2022 - 17:34 YangZhang  
sf_B_U-BESSEL_202203.datdat sf_B_U-BESSEL_202203.dat manage 2 K 28 Mar 2022 - 17:39 YangZhang  
sf_B_U-BESSEL_202204.datdat sf_B_U-BESSEL_202204.dat manage 1 K 04 May 2022 - 19:54 YangZhang  
sf_B_U-BESSEL_202205.datdat sf_B_U-BESSEL_202205.dat manage 928 bytes 04 May 2022 - 19:54 YangZhang  
sf_B_U-BESSEL_202206.datdat sf_B_U-BESSEL_202206.dat manage 919 bytes 06 Jun 2022 - 18:18 YangZhang  
sf_B_U-BESSEL_202209.datdat sf_B_U-BESSEL_202209.dat manage 673 bytes 06 Sep 2022 - 20:43 YangZhang  
sf_B_V-BESSEL_202201.datdat sf_B_V-BESSEL_202201.dat manage 500 bytes 27 Jan 2022 - 17:31 YangZhang  
sf_B_V-BESSEL_202202.datdat sf_B_V-BESSEL_202202.dat manage 1 K 02 Mar 2022 - 17:34 YangZhang  
sf_B_V-BESSEL_202203.datdat sf_B_V-BESSEL_202203.dat manage 673 bytes 28 Mar 2022 - 17:39 YangZhang  
sf_B_V-BESSEL_202205.datdat sf_B_V-BESSEL_202205.dat manage 1 K 06 Jun 2022 - 18:18 YangZhang  
sf_B_V-BESSEL_202209.datdat sf_B_V-BESSEL_202209.dat manage 1 K 06 Sep 2022 - 20:43 YangZhang  
sf_B_g-SLOAN_202202.datdat sf_B_g-SLOAN_202202.dat manage 1 K 14 Feb 2022 - 17:31 YangZhang  
sf_B_g-SLOAN_202203.datdat sf_B_g-SLOAN_202203.dat manage 2 K 25 Mar 2022 - 17:35 YangZhang  
sf_B_g-SLOAN_202204.datdat sf_B_g-SLOAN_202204.dat manage 1 K 04 May 2022 - 19:55 YangZhang  
sf_B_g-SLOAN_202205.datdat sf_B_g-SLOAN_202205.dat manage 2 K 06 Jun 2022 - 18:18 YangZhang  
sf_B_g-SLOAN_202209.datdat sf_B_g-SLOAN_202209.dat manage 909 bytes 06 Sep 2022 - 20:43 YangZhang  
sf_B_g-SLOAN_202210.datdat sf_B_g-SLOAN_202210.dat manage 798 bytes 27 Oct 2022 - 17:35 YangZhang  
sf_B_r-SLOAN_202203.datdat sf_B_r-SLOAN_202203.dat manage 971 bytes 09 Mar 2022 - 17:35 YangZhang  
sf_B_r-SLOAN_202204.datdat sf_B_r-SLOAN_202204.dat manage 2 K 04 May 2022 - 19:55 YangZhang  
sf_B_r-SLOAN_202205.datdat sf_B_r-SLOAN_202205.dat manage 1 K 06 Jun 2022 - 18:18 YangZhang  
sf_B_r-SLOAN_202209.datdat sf_B_r-SLOAN_202209.dat manage 1 K 07 Sep 2022 - 23:59 YangZhang  
sf_B_r-SLOAN_202210.datdat sf_B_r-SLOAN_202210.dat manage 978 bytes 26 Oct 2022 - 17:32 YangZhang  
sf_R_F972N20_202203.datdat sf_R_F972N20_202203.dat manage 1023 bytes 27 Mar 2022 - 17:39 YangZhang  
sf_R_F972N20_202205.datdat sf_R_F972N20_202205.dat manage 713 bytes 06 May 2022 - 00:09 YangZhang  
sf_R_F972N20_202209.datdat sf_R_F972N20_202209.dat manage 896 bytes 06 Sep 2022 - 20:43 YangZhang  
sf_R_I-BESSEL_202204.datdat sf_R_I-BESSEL_202204.dat manage 1 K 04 May 2022 - 19:56 YangZhang  
sf_R_I-BESSEL_202205.datdat sf_R_I-BESSEL_202205.dat manage 1 K 06 Jun 2022 - 18:19 YangZhang  
sf_R_I-BESSEL_202206.datdat sf_R_I-BESSEL_202206.dat manage 917 bytes 06 Jun 2022 - 18:18 YangZhang  
sf_R_I-BESSEL_202209.datdat sf_R_I-BESSEL_202209.dat manage 979 bytes 08 Sep 2022 - 00:00 YangZhang  
sf_R_R-BESSEL_202201.datdat sf_R_R-BESSEL_202201.dat manage 928 bytes 27 Jan 2022 - 17:31 YangZhang  
sf_R_R-BESSEL_202202.datdat sf_R_R-BESSEL_202202.dat manage 2 K 02 Mar 2022 - 17:34 YangZhang  
sf_R_R-BESSEL_202203.datdat sf_R_R-BESSEL_202203.dat manage 671 bytes 28 Mar 2022 - 17:39 YangZhang  
sf_R_R-BESSEL_202205.datdat sf_R_R-BESSEL_202205.dat manage 1 K 06 Jun 2022 - 18:19 YangZhang  
sf_R_R-BESSEL_202209.datdat sf_R_R-BESSEL_202209.dat manage 919 bytes 08 Sep 2022 - 00:00 YangZhang  
sf_R_R-BESSEL_202211.datdat sf_R_R-BESSEL_202211.dat manage 971 bytes 16 Nov 2022 - 17:35 YangZhang  
sf_R_V-BESSEL_202204.datdat sf_R_V-BESSEL_202204.dat manage 1 K 04 May 2022 - 19:56 YangZhang  
sf_R_V-BESSEL_202205.datdat sf_R_V-BESSEL_202205.dat manage 622 bytes 06 Jun 2022 - 18:19 YangZhang  
sf_R_V-BESSEL_202206.datdat sf_R_V-BESSEL_202206.dat manage 916 bytes 06 Jun 2022 - 18:18 YangZhang  
sf_R_V-BESSEL_202209.datdat sf_R_V-BESSEL_202209.dat manage 1 K 06 Sep 2022 - 20:43 YangZhang  
sf_R_Y-FAN_202203.datdat sf_R_Y-FAN_202203.dat manage 1 K 28 Mar 2022 - 17:39 YangZhang  
sf_R_Y-FAN_202205.datdat sf_R_Y-FAN_202205.dat manage 814 bytes 06 Jun 2022 - 18:19 YangZhang  
sf_R_Y-FAN_202209.datdat sf_R_Y-FAN_202209.dat manage 709 bytes 06 Sep 2022 - 20:43 YangZhang  
sf_R_i-SLOAN_202203.datdat sf_R_i-SLOAN_202203.dat manage 1 K 25 Mar 2022 - 17:35 YangZhang  
sf_R_i-SLOAN_202204.datdat sf_R_i-SLOAN_202204.dat manage 2 K 04 May 2022 - 19:56 YangZhang  
sf_R_i-SLOAN_202205.datdat sf_R_i-SLOAN_202205.dat manage 1 K 06 Jun 2022 - 18:19 YangZhang  
sf_R_i-SLOAN_202206.datdat sf_R_i-SLOAN_202206.dat manage 844 bytes 06 Jun 2022 - 18:18 YangZhang  
sf_R_i-SLOAN_202209.datdat sf_R_i-SLOAN_202209.dat manage 908 bytes 06 Sep 2022 - 20:43 YangZhang  
sf_R_i-SLOAN_202210.datdat sf_R_i-SLOAN_202210.dat manage 977 bytes 27 Oct 2022 - 17:35 YangZhang  
sf_R_r-SLOAN_202202.datdat sf_R_r-SLOAN_202202.dat manage 1 K 14 Feb 2022 - 17:31 YangZhang  
sf_R_r-SLOAN_202203.datdat sf_R_r-SLOAN_202203.dat manage 2 K 27 Mar 2022 - 17:39 YangZhang  
sf_R_r-SLOAN_202204.datdat sf_R_r-SLOAN_202204.dat manage 1 K 04 May 2022 - 19:56 YangZhang  
sf_R_r-SLOAN_202205.datdat sf_R_r-SLOAN_202205.dat manage 1 K 06 Jun 2022 - 18:19 YangZhang  
sf_R_r-SLOAN_202209.datdat sf_R_r-SLOAN_202209.dat manage 907 bytes 08 Sep 2022 - 00:00 YangZhang  
sf_R_r-SLOAN_202210.datdat sf_R_r-SLOAN_202210.dat manage 736 bytes 26 Oct 2022 - 17:33 YangZhang  
sf_R_z-SLOAN_202203.datdat sf_R_z-SLOAN_202203.dat manage 907 bytes 09 Mar 2022 - 17:35 YangZhang  
sf_R_z-SLOAN_202204.datdat sf_R_z-SLOAN_202204.dat manage 2 K 04 May 2022 - 19:56 YangZhang  
sf_R_z-SLOAN_202205.datdat sf_R_z-SLOAN_202205.dat manage 902 bytes 06 Jun 2022 - 18:19 YangZhang  
sf_R_z-SLOAN_202209.datdat sf_R_z-SLOAN_202209.dat manage 918 bytes 08 Sep 2022 - 00:00 YangZhang  
Topic revision: r208 - 01 Dec 2022, YangZhang
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