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THE INTERNATIONAL MARSWATCH ELECTRONIC NEWSLETTER
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Volume 4; Issue 3
March 18, 1999
Circulation: 1480
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Dear Marswatch participant,
Four items in this latest (somewhat long) installment of the newsletter:
(1) Where to find the latest jaw-dropping images from Mars
(2) Latest B.A.A. Mars observing update
(3) Latest A.L.P.O. Mars electronic newsletter
(4) Upcoming HST Mars observations
Also, remember that the 1998-1999 Marswatch Web Site is on line! To get to the
site, point (and bookmark!) your browser to: http://www.astroleague.org/marswatch/
Bert Stevens of the Astronomical League is keeping your posted images, ftp
upload/download site, and other information updated. Many spectacular images are
already posted!
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(1) Where to find the latest jaw-dropping images from Mars
Mars Global Surveyor has entered its mapping phase and is now beginning the
two-year process of taking images at up to 1.5 meter resolution (resolving
features about the size of your car!). The images are stunning and have
already revealed new surprises. It's a whole new planet, boys and girls.
Check out the data at:
http://www.msss.com/mars/global_surveyor/camera/images/index.html
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(2) Latest B.A.A. Mars observing update
Here is the most recent compilation of telescopic observations to date, from
Richard McKim of the British Astronomical Association. This and earlier
reports can also be found on the B.A.A. Mars reports page, at
http://marswatch.tn.cornell.edu/baa.html.
British Astronomical Association
Mars Section Circular 1998-99, No. 4
General
This Circular summarises the period 1999 February 1-28 (but with an incursion
into early March). On Feb 1, Ls = 91 deg., D = 7.9 arcsec., lat. of centre of
disk = 18 deg. N, with the planet's declination at 10 deg. south, some 5
degrees lower in the N. hemisphere skies than last month!
At my suggestion Jim Bell included Circular No. 3 in the last Marswatch
Electronic Newsletter, with a circulation of 1455 (only 1355 more than mine).
More good news is that next month marks the start of the main mapping mission
of Mars Global Surveyor. The craft has achieved its final, more circular
orbit, and will hopefully take many hi-res images. On the MGS webpage there is
now the 'Aerobraking Image Set' available for viewing and downloading.
Recommended.
National Geographic has just published a new Mars book with many recent
images. I have not seen it, but surely it will soon be out of date! (I am
hoping somebody will send me a Review copy!) A general interest article by
A.D.Andrews in the Irish Astronomical Journal was copied to me by Tony Kinder,
BAA Librarian. Titled 'The Leviathans of Tharsis' its scope is self-evident,
but I was surprised to find the BAA 1986 map, one drawing by myself, and
several other drawings by past BAA observers used as illustrations (Reference:
26 (1), 45-64 (1999)). John Rogers draws attention to several pieces in Nature
for 1999 February 18 (397, 560, 584, 586, 589 and 592) dealing with volcanism
on the early Mars, recent volcanism deduced from crater counts, dune-fields,
etc., as revealed by the MGS spacecraft during the early phase of its mission.
On Mars throughout February the N. polar cap appeared rather small, and at
some longitudes the dark rim seemed hard to see, or was absent. Parker's CCD
images sometimes showed some white haze just S. of the NPC, and this was the
case in the most recent images of March 3 (CM = 5-12 deg.). White cloud
activity presently remains high, and the Equatorial Cloud Band phenomenon
(ECB) has been very conspicuous in the CCD images, especially in blue light.
Elysium was brighter in the afternoon, and Hellas brightened considerably in
early February, being markedly lighter than in the previous month, sometimes
with a brighter spot in its NW corner. The 'Syrtis Blue Cloud' has been imaged
again by Parker. More observers are becoming active, and are sending in work:
thanks to S.Beaumont, A.W.Heath, Dr T.J.Richards and Dr R.Topping for recent
contributions.
Rik Hill emailed to say that his group at LPL were observing the planet every
fortnight (primarily to monitor atmospheric water vapour) with the 61-in
telescope at Catalina. He reports: "Our observations indicate the possibility
of enhanced dust south during the period a week to either side of 1 Feb." The
Director emailed early data about the Valles Marineris storm reported below,
although this event occurred a little later in February, as will be seen. I
have asked Rik for more details of his work.
Dust storm over Valles Marineris!
Rather than report the mundane, this month's Circular is devoted to the story
of a regional dust storm which was observed in the second half of February. On
February 21 David Gray (42-cm Dall-Kirkham Cass., with x262-x415, Spennymoor,
County Durham, Great Britain) observed considerable obscuration of the
markings and kindly notifed me at once by telephone. I immediately issued an
email alert to about 20 observers in Europe, the USA, Australia and Japan, and
telephoned several UK observers who are not on email. The response was
gratifying, although I have had no news from Japan as this issue goes to
press. Although we may not have caught the precise start of this regional
event, its decline and fall (as Gibbon might have written) was well followed.
I recently emailed Todd Clancy to ask whether the dust has had any measurable
effect upon martian atmospheric temperatures, as revealed through his radio
waveband work. Selected details of the observations follow:
Feb 19, 0700-0730 UT, CM = 101-108 deg, D.C.Parker, visual, 15-cm refl., from
Chiefland, Florida: Don emailed this observation after hearing about the
storm. He may have witnessed its start by noting a bright cloud on the
terminator: "It was very bright in integrated and blue light, but not
especially bright in red. On one occasion of excellent seeing, however, I
thought it had a peculiar hook shape, reminiscent of dust". This must have
been over Xanthe at the CML quoted, perhaps close to Aurorae Sinus. (I await
sight of Don's sketch.)
Feb 19, 1756 UT, CM = 261 deg, T.J.Richards (Victoria, W. Australia): A nice
CCD image with his 18-cm OG, showing the Syrtis Major side of the planet
completely normally and in fine detail.
Feb 21, 0210-0300 UT, CM = 12-24 deg, D.Gray: Most of the SW (S. following)
part of the disk was distinctly light, even in poor moments of seeing. A
brighter, elongated core was seen, especially in red (W25). This core was like
a 'V' on its side, with the apex occupying the N. part of Margaritifer Sinus,
one fork running along or close to the Valles Marineris, and the other running
off towards the SW limb, covering part of Mare Erythraeum. Margaritifer Sinus
was quite invisible. Sinus Sabaeus was well-marked, but the 'Forked Bay' area
(Sinus Meridiani) and the S. part of Mare Acidalium both seemed a little
obscured too. A more diffuse brightness covered the equatorial deserts from
the CM westward (Chryse, Xanthe, etc.), and this region was bordered on the E.
by a dusky curving streak. Nothing could be seen of Aurorae Sinus to the west.
Seeing was almost continually good throughout.
Feb 21, 0600 UT, CM = 68 deg, Hernandez (USA): N. Margaritifer Sinus and Mare
Erythraeum are faint. Agathodaemon (W. half of Valles Marineris, between
Aurorae Sinus and Tithonius Lacus) is dark. Chryse-Xanthe bright in red light.
To the west, Solis Lacus is dark, and that region appears normal. (I have not
yet seen the drawing made by Carlos; it was most useful that he observed a few
hours after Gray, so that his observation places limits on the W. side of the
dust storm.)
Feb 22, Gray: Very windy and with poor seeing. Mare Acidalium on the CM.
Bright cloud is again seen from about the CM to the following limb.
Feb 22, CM = 126-128 deg, F.J.Melillo (USA): Near-blank red light CCD images,
but on a small scale, and at too high CML to catch the storm.
Feb 23, 0520 UT, CM = 40 deg, Gray: In fine seeing he found the Aurorae Sinus
area very faint (and it is drawn very ill-defined), but the Margaritifer Sinus
and Mare Erythraeum regions have darkened again, and are as dark as M.
Acidalium. Agathodaemon is dark, as is Solis Lacus. Chryse-Xanthe is light, as
is the whole of the following part of the disk: Candor, Tharsis, Tempe. All
this light cloud has rendered Nilokeras faint, and Ganges nearly invisible. By
0600 UT the Chryse-Xanthe area was less bright. As ECB had been observed in
these longitudes before the event, there was probably a mixture of white cloud
and dust.
Feb 23, CM = 119 deg, S.Whitby (USA): With a 15-cm refl. Chryse-Xanthe bright
on the evening side, more so in red than in blue, but observer unable to see
anything else due to small aperture.
Feb 24, CM = 81-93 deg, Parker (USA), 41-cm refl., CCD work (and below):
seeing evidently not very good, but Solis Lacus dark. Strong ECB right across
the disk, including the evening Chryse-Xanthe. The Aurorae Sinus region is not
well placed.
Feb 26, CM = 15-25 deg, Gray: The S. features look much as on Feb 23 (Gray),
with Aurorae Sinus still weak. Equatorial cloud present. I have not yet seen
David's drawing of this date.
Feb 26, CM = 75 deg, Parker: Aurorae S. is present but not dark: seeing is not
very good. ECB evident.
Feb 26, T.Stryk (ALPO, observation passed on to me by Jim Bell): observer
remarked upon the region of Candor-Tharsis, that was bright in red light.
Certainly Candor is also light in Parker's February CCD images generally, but
whether it was enhanced during the storm I have not yet decided.
Feb 27, CM = 52-67 deg, Parker: As Parker, Feb 26.
Feb 28, CM = 33-61 deg, Parker: seeing looks better than on 24, 26, 27.
Aurorae Sinus looks normal in shape, but still perhaps less dark than usual,
as it is definitely not as dark as the (now clearly normal) E-W dark band of
the Mare Erythraeum. The ECB is incomplete at this CML, with some cloud in S.
Chryse-Xanthe, then unconnected cloud over Ophir-Candor-Tharsis on the a.m.
side. What is perhaps significant is that the images show the 'canal' known as
Hydaspes visible as a halftone streak curving its way from the W. side of
Margaritifer Sinus to somewhere about the SW side of Niliacus Lacus. This
feature is rarely seen, though it was recorded as being dark during 1858-1871.
Did it darken by surface excavation at the NE edge of the storm? I wrote the
above description before I read Don's own notes: he independently noticed the
Hydaspes, and drew attention to it.
March 3, CM = 5-12 deg, Parker: good seeing. My impression of this CCD image
is that some residual dust shows up very weakly as a thin E-W streak in red
light just N. of Mare Erythraeum, and that there is a distinctly brighter
cloud (dust) in red light just NE of Aurorae Sinus. Extensive but diffuse
brightness is seen in Chryse-Xanthe (perhaps brightest in red light), and in
Tharsis and Tempe (the latter regions were brightest in green and blue light).
There is an ECB from the p. terminator to the f. limb. The albedo markings
look very nearly normal to me on these images.
In character and evolution the February storm was not very different from
those of 1984 April (Ls = 132), 1990 October (Ls = 308) and 1997 June (Ls =
139), described in past BAA Section Reports by the undersigned. If we accept
the Feb 19 observation as marking the start, the storm was highly active and
near maximum on the 21st, but was already dispersing by Feb 23. On Feb 28 and
Mar 3 only traces of dust remained.
Thus the storm began near Ls = 99 deg., which is seasonally a bit early
compared with former telescopic events which definitely began over Valles
Marineris: my historical research shows that the earlier storms (1924-1990 and
?1879) occurred during the interval Ls = 132-357 deg., with most events near
the extreme limits. On the other hand, events which began in neighbouring
Chryse/Xanthe have occurred in the intervals Ls = 96-225 and 308-344 (from
records between 1903 and 1992), and the 1999 February event thus falls nicely
within the first interval. Anyone else out there with more observations of the
longitudes in question? Steve Lee emailed me to say that his group were to
have obtained time on the HST on March 3, under CM 300 deg., and their results
will be interesting to compare with Parker's on the same date (see above). HST
imaging is to be much less intensive than in 1997 this apparition, as noted in
an earlier Circular: the role of the ground-based observer is again underlined
by the our coverage of the dust event. (And who says it is always cloudy in
Great Britain?)
The next Circular
As I may be out of the country in early April I will attempt to issue a report
covering March 1-April 15 during the third or fourth week of April. Therefore
please report up to April 15 by, say, April 22.
Reporting data to the Section
I am always happy to receive CCD images by email. Any URGENT and important
drawing can be scanned and sent as an image file, but I do not want to receive
routine drawings by email, because the vast majority are sent as hard copies,
and that is the form I like to compare (and archive) them in. Send mail to
Cherry Tree Cottage, 16 Upper Main Street, Upper Benefield, Peterborough PE8
5AN, Great Britain; home telephone 01832-205387; home email
Rmckim5374@aol.com. (Do not use the former email address for my place of work
(mckim@oundle.northants.sch.uk).) Urgent faxes can be sent to my place of work
on 01832-274052.
Richard McKim, Director, 1999 March 7
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(3) Latest A.L.P.O. Mars electronic newsletter
The Martian Chronicle: Newsletter of the International Mars Patrol
An Observing Program of the Association of Lunar and Planetary Observers
Daniel M. Troiani
ALPO Mars Section Coordinator
E-Mail: dtroiani@triton.cc.il.us or dantroiani@Earthlink.net
ALPO Home Page: http://www.lpl.arizona/~rhill/alpo
February, 1999
OPPORTUNITY TO STUDY MARTIAN NORTHERN MID-SUMMER
With Martian northern summer solstice having just passed, characteristics
of the aphelic summer on Mars can be studied as the planet is approached by
Earth in coming weeks. Among those characteristics is not just the greater
Mars-sun distance but the fact that this season will be nearly six Earth
months long and opposition is virtually in the midst of it.
We can anticipate the shrinkage of the NPC and, as Jeff Beish has informed
us in a recent Chronicle article, the possibility of vigorous dust storm
activity from Chryse to just west of Solis Lacus. Already the anticipated
water-ice clouds of late Martian northern spring have been reported and
imaged with exceptional clarity despite distances to the planet of about
1.3 AU. Fog over Hellas has also been reported. It is so good to know
that Don Parker's 16" f/6 Newtonian is operational again!
Of course the study of the cloud patterns (and their gradual demise as the
season wears on) is best done with blue filters whether the observation is
carried out visually, photographically or electronically. The most salient
observations may be those which detect the last residuals of the clouds
(which may be in the form of "limb arcs") or the first traces of dust
activity, irrespective of location, which of course is now recognized to be
best accomplished with red filters.
Perhaps a reminder is in order here to make sure everyone is aware that all
prior literature (of which there are volumes) that assign yellow filters to
dust detection is obsolete. They may be quite sensitive to dust storms but
so much of Mars is bright in yellow that the dust can be masked. It might
still be wise, however, to try yellow filters (with IR rejection, of
course) using electronic imaging systems when the dust season is imminent.
With the official commencement of the Mars Global Surveyor mission
scheduled for April, no doubt there will be public awareness going into the
prime period of the apparition, something which seems to have never
happened with a mission before. And it wouldn't have if the aerobraking
maneuver to circularize the orbit had not been delayed by the faulty solar
panel strut. This might be a PR break we could use, since expertise in all
things Martian, Disney Studios or no, is rather scarce. The major media
will want to satiate the public appetite for the latest findings about
Mars, and who better to turn to than the Mars Section? If at all possible,
public observing sessions might be wise this time around also, especially
since the weather should be tolerable.
EARLY REPORTS/OBSERVATIONS
The price we pay for opposition occurring in balmy spring weather is that
we suffer through the early part of the apparition in less than clement
weather. With the usual exception down in South Florida, observers have
been expressing frustration with sky conditions (and in the case of the
undersigned, a nasty flu bug). Intrepid students of Mars have, however,
begun to send in their impressions.
Besides the already posted to the Mars Section internet site imagery from
Don Parker, we have heard from Frank Melillo, Richard McKim, Joao Porto,
Damien Peach, David Gray, Nicolas Biver, Johan Warell and observations
posted on the O.A.A. WEB site. The accentuated northern tilt in our favor
has enabled reasonably good study of the NPC. Its steady retreat can be
seen despite the unfavorable angular diameter, and so far we have these
reported trends/characteristics. Warell has the cap as "brilliant white"
on January 11; some of Don Parker's imagery reveals the cap to have subtle
gradations of intensity, with the brightest possibly the feature noted on
December 25 following the CM, which then was 310 degrees. It is apparent
both in the composited RGB imagery and in red light. Cap "outliers",
portions which remain in place as surrounding cap disappears and vanish
themselves later on, have become noticeable. Olympia is foremost of these
and seems to be emerging in Parker's January 9 imagery (CM 170 degrees),
very near the expected time.
Among the highlights of atmospheric activity include equatorial cloud bands
(ECB's, get used to them!), orographics, especially over Tharsis/Nix
Olympica, fog, the "Blue Scorpion" and limb features. Since they are
apparently resultant from NPC retreat, they have been expected. Can we
expect to see the converse - the cap returning as the clouds disappear?
Probably at best there will be only vague hints, as the north cap angle
itself becomes unfavorable. The dynamics of the converse are probably not
a mirror image in any case and may be disparate enough to suggest the term
"converse" is inapplicable. The formation of the polar hood prior to the
cap is in all likelihood the remnant of the clouds. Except for the fog,
noted in the impact basin Hellas, all the formations are probably high
altitude ice crystal "cirrus"-like structures.
Many thanks to Richard McKim of the BAA, who has once again sent in many
noteworthy observations of his and those of his colleagues, and for his
astute interpretations of Martian activity and features. The next
Chronicle, out soon, will detail many of these reports.
Daniel M. Troiani
ALPO Mars Section Coordinator
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(4) Upcoming HST Mars observations
Just a heads-up to those interested in obtaining observations simultaneous
with the Hubble Space Telescope: The next (and only!) set of HST Mars
opposition observations are currently being scheduled, and are slated to
occur during the week of April 26 to May 4. The images will be posted to
the Web as soon as I get them. Details on specific observing times will
be forthcoming in a future newsletter.
Keep those cards and letters coming!
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Other Useful and Related WWW sites:
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Latest MGS images:
http://www.msss.com/mars/global_surveyor/camera/images/index.html
Main MGS Home Page:
http://mars.jpl.nasa.gov/mgs/index.html
Mars-98 Orbiter:
http://mpfwww.jpl.nasa.gov/msp98/orbiter/
Mars-98 Lander:
http://mpfwww.jpl.nasa.gov/msp98/lander/
Mars-98 MVACS Science Payload Home Page:
http://mvacs.ess.ucla.edu/index.html
New Millenium Mars Microprobe Mission (DS2):
http://nmp.jpl.nasa.gov/ds2/
Pathfinder Home Page:
http://mars.jpl.nasa.gov/default.html
JPL Mars Missions Page
http://www.jpl.nasa.gov/mars
Mars-01 and Mars-03 APEX/Athena Science Payloads
http://astrosun.tn.cornell.edu/athena/index.html
A.L.P.O. Mars observations:
http://www.lpl.arizona.edu/~rhill/alpo/mars.html
Astronomical League:
http://www.astroleague.org/
1998-99 Marswatch ftp site and imaging highlights:
http://www.astroleague.org/marswatch
1996-97 Marswatch highlights:
http://mpfwww.jpl.nasa.gov/mpf/marswatch.html
Mars (and other) Educational Resources Page
http://marswatch.tn.cornell.edu/marsidea
MarsNet:
http://astrosun.tn.cornell.edu/marsnet/mnhome.html
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I will continue to maintain the email distribution list as well
as the various Cornell and JPL Marswatch-related WWW archives.
If you are receiving duplicate copies of this mailing, or you want
your name removed from the distribution list, please send me email.
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Jim Bell
Cornell University
Department of Astronomy
Center for Radiophysics and Space Research
402 Space Sciences Building
Ithaca, NY 14853-6801
phone: 607-255-5911; fax: 607-255-9002
email: jimbo@marswatch.tn.cornell.edu
WWW: http://marswatch.tn.cornell.edu
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