Issue 6: 14th May 2002
Welcome to the CDS Newsletter. The goal of this Newsletter is to inform the CDS user community of
This Month's Topics:
Medoc Campaign #9 will take place 20 May - 02 June. CDS will support several observing programmes, listed on the SOHO monthly calendar at:
CDS Planning from RAL
At present, new CDS planners who are non-US citizens require an escort at GSFC, which can be restrictive both for the planner and the local GSFC personnel.
Anyone who wishes to be a CDS planner outside the periods of the Medoc campaigns, may consider planning from RAL as an alternative to travelling to GSFC. This could be a particularly convenient and cost-saving option for UK-based scientists. All first-time planners are provided training at RAL before their planning week, and local support will be given during the planning week.
Please contact Andrzej to inquire about the current planning schedule and to arrange dates.
In my experience, being a planner during your own campaign or joint observing programme offers a considerable advantage in that it affords you direct control over target selection and pointing, in response to current solar conditions. I would like to encourage everybody, particularly PhD students and post-docs, to consider this hands-on way of acquiring data for your research projects. - Andrzej Fludra
CDS User Guide
This is a reminder that the CDS User Guide is available at:
ANYONE WHO WANTS TO PROPOSE A NEW CDS STUDY OR BEGIN THE DATA ANALYSIS IS STRONGLY ENCOURAGED TO CONSULT THIS MANUAL.
Users who find things they don't understand, or that don't work, or information that is missing, should contact a member of the RAL CDS team (for example, Dave or Andrzej). Your feedback is very important to us, as we cannot solve problems we do not know about. We will endeavour to solve any problem that is brought to our attention. - Andrzej Fludra
The User Guide also contains information on browsing and retrieving CDS data, in particular, links to SOHO archives at RAL, in the USA and France.
Here are direct addresses of these archives:
http://trace.solararchive.rl.ac.uk/soho/ - RAL
http://sohowww.nascom.nasa.gov/catalog/ - USA
http://www.medoc-ias.u-psud.fr/archive/ - France
Please note that the RAL archive and the USA archive have different interfaces. They are reasonably intuitive and include links to their respective Help files. Should you encounter an insurmountable problem when accessing the archives, please email your questions to the local archive administrator listed on each website. - Andrzej Fludra
Oscillations Above Sunspots
N. Brynildsen, P. Maltby, T. Fredvik, and O. Kjeldseth-Moe, 2002, Solar Phys., in press.
The 3 min oscillations in the sunspot atmosphere are discussed, based
on joint observing with the Transition Region And Coronal Explorer -
TRACE and the Solar and Heliospheric Observatory - SOHO. We find that
the oscillation amplitude above the umbra increases with increasing
temperature, reaches a maximum for emission lines formed close to 1 -
2x10^5 K, and decreases for higher temperatures. Oscillations
observed with a high signal to noise ratio show deviations from pure
linear oscillations. The results do not support the sunspot filter
theory, based on the idea of a chromospheric resonator. Whereas the
filter theory predicts several resonant peaks in the power spectra,
equally spaced ~1 mHz in frequency, the observed power spectra show
one dominating peak, close to 6 mHz. Spectral observations show that
the transition region lines contribute less than 13 percent to the
TRACE 171 A channel intensity above the umbra. The 3 min oscillations
fill the sunspot umbra in the transition region. In the corona the
oscillations are concentrated to smaller regions that appear to
coincide with the endpoints of sunspot coronal loops, suggesting that
wave propagation along the magnetic field makes it possible for the
oscillations to reach the corona.
The present paper compares off-disk spectral observations of the solar
corona in the ranges 307-379 A and 513-633 A with theoretical
emissivities calculated using the CHIANTI database. The observed
spectra were recorded by the Coronal Diagnostic Spectrometer
instrument on board the Solar and Heliospheric Observatory using the
Normal Incidence portion of the instrument.
Flights of the SERTS sounding rocket were made in 1997, 1999, and 2000
to provide updated radiometric and wavelength calibrations for several
experiments on the SOHO satellite mission. Just before or after each of
these flights, end-to-end radiometric calibrations of the rocket payload
were carried out using an EUV transfer standard light-source specially
re-calibrated against the primary standard of BESSY I. These measurements
established the absolute SERTS responsivity within a relative uncertainty
of 17% over its bandpass of 30 nm to 36 nm. During the flights, SERTS and
SOHO CDS observed the same solar locations, as demonstrated by subsequent
data co-registration with simultaneous SOHO EIT images, allowing the SERTS
calibrations to be directly applied to both CDS and EIT. Following is a
brief summary of the SERTS-97 radiometric calibration and the underflight
cross-calibration that it provided for the CDS NIS channels at a time
shortly before SOHO's temporary loss of pointing control in 1998.
From the CDS Operations Management Team in the Space Science & Technology Department at CCLRC Rutherford Appleton Laboratory
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