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Proposal Identification No.: A1380 Date Received: 2005­Nov­11 01:21:21
Technical Page
Proposal Type: Urgent
General Category: Astronomy
Sub­Category: Spectroscopy
Observation Category: Solar System
Total Time Requested: approx. 25 Hours
Proposal Title: Radio OH Observations of Comet C/1994 S4 LINEAR
ABSTRACT:
In comets, a strong observed 18­cm OH line can be produced as the comet amplifies or absorbs background
radiation. In highly productive comets, OH spectral lines in the inner coma appear weaker than expected because
gas collisions thermalize and ''quench'' this maser emission. The role of such collisional quenching was recently
shown to play a large role in Comet Hale­Bopp, one of the most productive comets ever observed. The goal of this
study is to achieve high­resolution observations of a less­productive, more ''typical'' long­period comet, in order to
investigate the degree of quenching. The close apparition of the newly discovered comet C/1999 S4 LINEAR
a#ords an opportunity to resolve the gas coma and observe how the OH lines vary with distance from the nucleus,
constraining the degree of line quenching at work in the coma.
Name Institution E­mail Phone Student
Amy J Lovell FCRAO/Amherst
College
ajlovell@amherst.edu (413) 542­8479 no
None No
All of the observing run. Maybe
Part of the observing run. Yes
Queue Observing
Instrument Setup
L­wide
Atmospheric Observation Instruments:
Special Equipment or setup: none
RFI Considerations
Frequency Ranges Planned
1612
1665­1667
1720
1