Overview of SPIRE Photometer Pipeline

Transcription

1 8 th Feb 2012 Overview of SPIRE Photometer Pipeline C. Kevin Xu (NHSC/IPAC) page 1

2 8 th Feb 2012 Goals: Show how SPIRE Photometer pipeline works (functionalities of major modules). Explain what is new in HIPE 8. Brief summary of remaining issues. Will concentrate on scan map user pipelines (covering small map, large map, SPIRE/ parallel mode). page 2

3 8 th Feb 2012 User Pipelines User pipelines (Jython scripts): Simplified version of Standard Product Generation (SPG) pipelines. You can find these user pipelines in HIPE: page 3

4 8 th Feb 2012 SPIRE Pipeline & Data Products 5 (in HIPE) Our focus ( user pipelines ) page 4

5 8 th Feb 2012 Scan Map Pipeline Flow Chart A reversed sequence relative to the chain of data acquisition Baseline removal + Mapper page 5

6 8 th Feb 2012 Scan Map Pipeline Flow Chart A reversed sequence relative to the chain of data acquisition place-holder Baseline removal + Mapper page 6

7 8 th Feb 2012 Scan Map Pipeline Flow Chart A reversed sequence relative to the chain of data acquisition place-holder Default: wavelet deglitcher Alternative: σ-κ deglitcher Baseline removal + Mapper page 7

8 8 th Feb 2012 Scan Map Pipeline Flow Chart A reversed sequence relative to the chain of data acquisition place-holder FFT based (run after deglitch & repair to avoid ringing) Baseline removal + Mapper page 8

9 8 th Feb 2012 Scan Map Pipeline Flow Chart A reversed sequence relative to the chain of data acquisition place-holder Include: (1) Non-linearity correction (2) Volt to Jy/beam conversion Baseline removal + Mapper page 9

10 8 th Feb 2012 Scan Map Pipeline Flow Chart A reversed sequence relative to the chain of data acquisition place-holder Remove 1/f noise due to T-drift Baseline removal + Mapper page 10

11 8 th Feb 2012 Scan Map Pipeline Flow Chart A reversed sequence relative to the chain of data acquisition place-holder FFT based Baseline removal + Mapper page 11

12 8 th Feb 2012 Scan Map Pipeline Flow Chart A reversed sequence relative to the chain of data acquisition place-holder Telescope pointing & orientation SPIRE detectors positions Baseline removal + Mapper page 12

13 8 th Feb 2012 Scan Map Pipeline Flow Chart A reversed sequence relative to the chain of data acquisition place-holder Choices: Default: scan median baseline removal Advanced : polynomial baseline removal Most advanced: an iterative destriper Baseline removal + Mapper page 13

14 8 th Feb 2012 Scan Map Pipeline Flow Chart A reversed sequence relative to the chain of data acquisition place-holder Choices: Default: scan median baseline removal Advanced : polynomial baseline removal Most advanced: an iterative destriper Baseline removal + Mapper Default: naïve mapper Alternative: madmapper page 14

15 8 th Feb 2012 Scan-By-Scan Processing The pipeline processes timelines scan by scan (to ease the demand on RAM). Problem: ringing at the two ends of each scan due to FFT based modules. Solution: (1) Before the process, attaching turn-around data blocks to ends of the scan. (2) During the process, the ringing is confined to the turn-around data. (3) After the process, cut-off the turn-around data blocks from the scan. Uniform scan speed distance Turnaround page 15

16 8 th Feb 2012 Highlights of a User Pipeline (Jython Script) page 16

17 8 th Feb 2012 Highlights of a User Pipeline (Jython Script) New in HIPE 8.0 (for extended source, optional) page 17

18 8 th Feb 2012 Signal Jump Sudden (spontaneous?) jump in the timeline of a single channel. Mostly seen in thermistors (see below). Very rarely seen in detectors. The average frequency is ~ 1/day ( a few hundred instances since launch). The cause is still unknown. Effect: The pipeline uses thermistor timelines in the correction for detector signal drift due to bath temperature drift (major source of 1/f noise for SPIRE). A thermistor jump affects this correction, introducing artificial stripes in the final map. Jump Stripe caused by the jump page 18

19 8 th Feb 2012 Thermistor Jump Solution (in HIPE 8.0) New module Jump Detector (automatically identify & mask any thermistor affected by a jump) a reversed sequence relative to the chain of data acquisition scan by scan processing Destriper + Mapper Exclude masked thermistors page 19

20 8 th Feb 2012 Status of SPIRE Scan Map Pipeline in HIPE 8.0. SPIRE 3-color map of NGC 5315 (a planetary nebula) General assessment: In many cases, data from HSA are already science quality! The official calibration accuracy is ±7% (5% from model, 2% RMS). An example (on the right): The image from HSA looks good. Caveat: detailed inspections show thin stripes (can be improved using a more advanced baseline remover such as the iterative destriper). A major issue yet to resolve: stripes due to bias voltage drift (the burp ) (affecting a few observations) (Public data taken from HSA) page 20

21 8 th Feb 2012 Bias Drift in Burp Period Every time when SPIRE is switched on after a cooler recycle, the first ~6 h sees a rapid rise of bias voltage (the burp ). This effect has not been corrected in pipeline. It causes stripes in maps observed during the burp period (see example below). A pipeline module is now being developed to correct this effect (available soon). For point source surveys, the stripes might be removed by polynomial baseline removal. Resistor voltage After cooler recycle 1 (~40 h) After cooler recycle 2 (~40 h) An example of stripes caused by bias drift Bias voltage bias drift ~10σ burp ~ 6h (Standard pipeline product) page 21

22 8 th Feb 2012 Summary Scan-Map pipeline covers nearly all SPIRE PHOT AOTs (small map, large map, map in SPIRE/ parallel mode). It follows a reversed sequence relative to the chain of data acquisition. For a general user, Level0_5 should be the best starting point. From Level0_5 to Level 1, the pipeline processes any observation data set scan by scan (to ease the demand on the RAM). The current pipeline (HIPE 8.0.1) does a good job ( science ready ) in general. However, the pipeline still has some open issues: that (1) Stripes due to the burp effect (affecting ~10% observations). (2) Residual stripes (can be corrected by the destriper module in HIPE). (3) Residual glitches in maps (2nd level deglitcher being developed inside the destriper module). page 22

23 8 th Feb 2012 Home work: Run Photometer Large Map user pipeline (with your own data or NGC 5315 data). Next: A demo of SPIA (SPIRE Photometer Interactive Analysis), a GUI based data reduction tool (including all pipeline modules and more). page 23