Here you find the answers to some frequently asked questions about FORS1 SM
data processing and distribution. If you do not find the answer to your questions
here, do not hesitate to contact
us.
SM DATA PIPELINE
PROCESSING
Which Instrument modes
are pipeline supported?
The following modes are currently pipeline supported:
IMAGING (bias and flat-field correction);
LONG SLIT
and MOS spectroscopy (bias, flat-field and 2D-wavelength
calibration, distortion correction (not for LSS), sky subtraction and
extraction of object spectra);
If you want to use the spectroscopic FORS1 pipeline you can download
it from here.
Can I use the pipeline reduced data for scientific purposes?
You can certainly use the reduced imaging. The 4 port removal
is good to within ~1ADU and the flat-fielding accuracy is of the
order of 5%. For long slit spectroscopy one should be more careful,
since the flat field normalization is still not yet optimized
and some reflections due to the LADC are introducing artifacts on
the reduced science frames.
Are there any plans to extend the pipeline support to other instrument
modes?
Yes. Currently the Pipeline Development Group is working on supporting
pre-reduction (debiassing, flat-fielding) of IMAGE POLARIMETRY (IPOL)
SCIENCE data.
I am a Visitor Mode user. Can I use the FORS1 pipeline to reduce my data?
The spectroscopic FORS1 pipeline is available from here.
I have received my Service Mode data. I have noticed that the master
calibrations are smaller than the raw frames. Can anybody tell me why
and what I should do to use them?
The current version of the FORS1 pipeline trims the pre-scan regions in
all processed frames, including master products. For the location of these regions see here for the old CCD (until March 25, 2007) and here for the new CCDs (since March 28, 2007). If you
want to use the pipeline master calibrations to reduced unprocessed
data, you have to trim the raw data accordingly.
I want to use the zero points I found on the web to calibrate my
pipeline reduced imaging. How should I proceed?
First of all you should proceed with great care. These zeropoints are
intended for instrument monitoring and not for scientific calibrations
(see here). The
photometric zero points logged on the web pages are normalized to
electrons/second and corrected with default colour and
extinction terms (airmass 0), which may deviate from the actual ones
(see here). To
apply such zero points to the images reduced by the FORS1 pipeline
included in your SM package, you have to multiply the measured flux
values (ADU) by the average
conversion factor.
SM DATA
DISTRIBUTION
Where can I find information
about the execution status of my Service Mode programme?
This information is provided by the User Support Department and can be retrieved
using the following form.
When will I get my Service
Mode data?
A service mode package is prepared by QC and the DVDs are burned by
the Archive Team once the User Support Department has declared a program completed.
For the general policy, have a look here.
Usually the programmes are packed within one month from the User Support Department
request. This time interval takes into account:
- the time taken by the data to be shipped and received by the Archive in Garching (usually one week)
- the time required by QC to download, process and certify the data quality
- the time required by QC to prepare the data package
- the time required by the Archive to burn and ship the DVDs
Data packages normally reach the PI within 1-2 weeks after being burned.
Do I have to submit a
request to receive my Service Mode data package?
No. Service Mode programmes are declared completed by the Users Support
Department. This signal is sent to the Data Flow Operations Group which then prepares
the SM package. The data are copied onto CDs/DVDs and sent to the PI as soon
as possible.
Is it possible to have
a partial release of my Service Mode data before the programme is completed?
As a general rule, no. Exceptions are pre-imaging and special programmes.
For the general policy have a look here.
SM OBSERVING
Where can I find general information about the Service Mode Observing?
A complete description of Service Mode Observations can be found here.
Support during the preparation of SM observations is given by the User's
Support Department.