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Observing notes for the November 1998 2dF run

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Night-by-night updates | Observing summary | Reductions and data

Night-by-night updates

11/11-12/11

Cloudy All Night Positioner running slightly slower than expected. Some gripper failures.

12/11-13/11

Fog and Thunderstorms Some more gripper failures

13/11-14/11

Clearish at Sunset, storms to the East, but these had already passed over the observatory. few minutes lost between 1st and second field due to an IPL glitch that prevented the telescope slewing, cured by a soft reset for the first time ever. 20 minutes lost due to an IP stack overflow on the control terminal 6 minutes lost in the middle of the third field while the zgear was adjusted. 5-10 minutes lost at end due to a gripper failure. 15 minutes lost at the start of the 4th field due to an XMEM crash 5 fields observed in all. SGP237 is a repeat observation from January.

1. sgp115 3x1200s pretty clear
2. sgp190 3x1200s some cloud passing through second frame.
3. sgp191 3x1200s pretty clear
4. sgp224 3x1200s seeing going off, pretty clear
5. sgp237 3x1200s moon up, clouds visible

14/11-15/11

Clear all night, transparency maybe a little poor. Observed 1st field (galaxies only) in 45 minutes, starting 15 minutes before end of twilight (an extra frame was obtained before this but made no change to the redshift completeness. Configuration time is roughly 1h20m, so in principle we should be able to observe six fields tonight. QSO at z=1.54 found at TGS059Z150 in a galaxy only field, and another at z=0.9 at TGS114Z079, also in a galaxy only field. Data reduction for SGP179 proved problematic for chip 2 due to what appeared to be an object in one sky fibre which had not shown up in eyeballing (possibly a high PM star?), and problematic on chip one as CR rejection seemed to have failed. SGP194 looks like it might have another boundary problem, from a UKST plate that has no previous fields observed on it (471/537). Halation is returning to chip 2, giving a systematic drop of ~5% in completeness between spectrographs. Two further QSOs were detected on fields SGP224 and SGP164 (again a galaxy only field).

1. sgp059 3x900s clear 1.5''
2. sgp114 3x1200s clear
3. sgp179 3x1200s pretty clear
4. sgp194 3x1200s
5. sgp221 3x1200s
6. sgp164 3x1200s

15/11-16/11

Clear at start of night Observed 1st field (galaxies only) in 45 minutes, starting 10 minutes before end of twilight, with 96% completeness. Long (1h20m) configuration time appears to be due to erroneous error tables in a few groups of fibres (same groups on each plate), and the cause of this is being investigated. Some thin clouds about for the second half of the night, but clear to +/- 60 degrees ZD at sunrise.

1. sgp061 3x900s clear 1.5''
2. sgp258 3x1200s clear
3. sgp185 3x1200s pretty clear
4. sgp202 3x1200s some clouds passing through
5. sgp315 3x1200s
6. sgp162 3x1100s E-W plate boundary drop.

16/11-17/11

Clear at start of night... sudden drop in temp ~45 minutes after sunset -> seeing went off. Lost ~30 minutes due to an oil pressure alarm on the telescope right at the start of the night, but we put in a change to the gripper jaw opening code sequence which appeared to gain ~10 minutes/field by speeding each move (this is basically what we turned off at the start of the week to improve reliability, but the new version seems to be somewhat more robust.) Configuration time for a typical field was therefore equal to total time required for an exposure plus overheads 4th field observed with ADC null due to a software glitch. Closed dome at end of the third frame on this field as fogging up. Last frame was lost due to an XMEM crash. Skipped the 5th field while the dewpoint was high, and scraped 40 minutes on a final galaxy only field.

1. sgp060 3x900s clear 2''
2. sgp257 3x1200s clear
3. sgp192 3x1200s clear, humidity rising
4. sgp213 2x1200s ADC nulled ZD=30 degrees at start, fogged up
5. sgp163 2x1200s

Night-by-night updates | Observing summary | Reductions and data

Observing summary

The following summary gives the civil date of observation, field name, exposure time, nominal numbers of galaxies and QSO candidates in the field, the redshift yield for the galaxies (the fraction with Q=3,4 redshifts) and an indication of conditions.

Date   Field  Exposure #gal #QSO Yield      Comments

981113 SGP115  3x1200s  331    0  96%     Clear, 1.5''  
981113 SGP190  3x1200s  251   92  96%     Some Cloud
981113 SGP191  3x1200s  247   99  94%       
981113 SGP224  3x1200s	264   80  95%     
981113 SGP237  3x1200s  254   84  97%     Perfectly Clear, some moon 2.1''
981114 SGP059  3x900s   327    0  92%
981114 SGP114  3x1200s  346    0  92%
981114 SGP179  3x1200s  247  103  91%     looks like CR-rejection failed
981114 SGP194  3x1200s  292   55  88%
981114 SGP221  3x1200s  267   78  94%
981114 SGP164  3x1200s  337    0  95%     1.5'' at +4h, 1.3'' at zenith.
981115 SGP061  3x900s   343    0  95%     1.5'' 
981115 SGP258  3x1200s  189  154  88% 
981115 SGP185  3x1200s  261   79  96% 
981115 SGP202  3x1200s  292   62  94%     some thin clouds passing through
981115 SGP315  3x1200s  194  143  96%     really nice spectra!!
981115 SGP162  3x1100s  349    0  94%     clear, 1.5'' seeing.
981116 SGP060  3x900s   345    0  93%
981116 SGP257  3x1200s  196  151  96%
981116 SGP192  3x1200s  257   91  94%
981116 SGP213  2x1200s  268   78  95% fogged out. Closed as XMEM lost 3rd read
981116 SGP163  2x1200s  352    0  89% finished in twilight -poor

Reduced data from the September run

The following table gives the completeness from re-reduced data from the September run. See the September observing notes for a full description of these data.

Date   Field  Exposure #gal #QSO Yield  Comments

980913 SGP180  3x1200s  233  104  97%
980913 SGP181  3x1200s  243   91  96%  
980913 SGP182  3x1200s  237   98  88%  
980913 SGP183  3x1200s  276   72  67%   Plate Corner astrom problem
980913 SGP184  4x1100s  264   82  94% 
980913 SGP209  3x1200s  249   97  96%  
980913 SGP249  4x900s   224  136  93%  

Night-by-night updates | Observing summary | Reductions and data

Reductions were done during the night. Some frames appear to suffer from poor subtraction of the diffuse scattered light component, so this was turned off for most of the reductions.

Summary