[AZ-Observing] Most Distant Galaxy, 3C 273 in a Pronto
- From: Brian Skiff <Brian.Skiff@xxxxxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Sat, 2 Apr 2005 01:22:43 -0700 (MST)
Those who attended my talk at the SAC meeting last Friday extolling the
virtues of "minimal astronomy" may find this of (minimal) interest.
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"Most Distant Galaxy" is the title of an atmospheric jazz piece by the
soprano saxophonist Jane Ira Bloom, my favorite jazz composer. In a setting
for soprano, bass, and electronic percussion, she evokes not so much loneliness
as a keening, isolated alone-ness, for which a subtly turned blues phrase is
particularly apt.
A much more prosaic enterprise tonight for me was hunting down the
brightest quasar, 3C 273, in my little 70mm Pronto telescope. Though not
nearly the most distant galaxy known, it is probably the most distant object
visible in such a small instrument. The redshift is about z = 0.16,
corresponding to about 2 billion light-years. It is not especially faint for
this telescope, so this was mainly an exercise to be able to say I'd done it.
As usual I observed from the 'true dark' Lowell Anderson Mesa site,
in this instance from the observing floor of our 1.1-m telescope, with which
I am doing spectroscopy tonight. Len Bright of the Lowell staff is running the
seeing monitor a hundred meters away, which at the time of the observations was
showing image quality of just 0".7---another nice night! Temperature was a
balmy 39F = 5C. By way of preparation, I had Alan MacRobert's article in the
May 2005 issue of 'Sky & Telescope', and also a large-scale chart from the
AAVSO Web site that shows the immediate field along with magnitudes for stars
in the area.
Earlier this evening the German variable-star observer Wolfgang Renz
posted a note to the AAVSO discussion-list pointing out that the asteroid
(329) Svea, at V mag 12.7, was passing through the field. It confused him at
first, since it is similar in brightness to the quasar, and (obviously) not
plotted on the chart. Not knowing about the asteroid would certainly have
confused _me_, so I'm glad to have had the warning.
The main difficulty in the observation was simply getting to the field,
since I do without a finder, Telrad, etc. The chart in MacRobert's magazine
article was just about ideal for star-hopping at 30x from eta Virginis.
I first used 75x to zero-in on the quasar and faint field stars, which lie
northwest of a mag 10.3 star that is the tip of an arrowhead asterism (see S&T
chart). To secure the identification, I was especially wanting to pick up the
mag 13.5 star just west of 3C 273---if I could see the pair resolved, then I
would know I'd seen the quasar, and some of those 2-billion-year-old photons
had hit my eye. Though I could see the asteroid a bit north of where the
quasar was plotted on the AAVSO chart, and a mag 12.7 star not far south,
I wasn't sure about 3C 273.
I changed to 95x (4.8mm Nagler), settled in for another look, and saw
the QSO/comp-star pair almost right away, along with the other stars and the
asteroid. QED. The ASAS-3 robotic photometry system measured the quasar at
V=12.6 two nights ago; it appeared noticeably brighter than than the mag 13.5
star tonight. I got a few more looks before having to attend to the bigger
telescope, which necessitated shifting the dome-slit around to the north,
ending viewing of Virgo for the moment.
\Brian
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