Bright ast. occâns, TONIGHT Klotho -n.Vegas,Flagstaff,nPayson,LasCruces; Oct.
31 Yrsa â Tucson,Socorro
After our multiple-stations success with the relatively bright (but low
altitude) (16) Psyche occultation Wednesday night, we have chances for two
brighter stars, at higher altitude, to be covered by other large asteroids
later this month. Even if you canât travel to the paths, it would be useful
to observe from your home, in the small but possible chance that you could
observe, or record, with high S/N, a brief occultation by a moon of one of
these asteroids. The Oct. 31 st Yrsa event could be important since VERITAS
(near Amado, s. of Tucson) plans to try to observe it to measure the starâs
angular diameter, and other chords would be valuable for their analysis.
_ _ _
First, TONIGHT (2019 Oct. 25 MDT) at 10:50pm MST (10:49pm PDT n. of Las Vegas,
and 11:51pm MDT in Las Cruces; itâs 5h UT of Oct. 26 UT), there will be an
occultation of 9.8-mag. PPM 148311 (= TYC 0102-01567-1, spectral type G0) in
western Orion by the 91-km asteroid (97) Klotho for up to 17s with a strong
1.2-mag. drop. Two observers in northern California plan to cover the northern
half of the shadow, so it would be great if others near the center (Flagstaff
and Las Cruces) could observe, or some travel to the southern part of the path
a little north of both Las Vegas and Payson (AZ), to obtain good coverage
across the asteroid. In the Phoenix area, the altitude will be 22 deg. in the
east (azimuth 101 deg.), but it will be close to that from s. Nevada, across AZ
and s. NM, and a few degrees higher in s. NM. The target star is at J2000 RA 5h
01m 06.0s, Dec +02 deg. 58' 05", 1.7 deg. east-northeast of 3.7-mag. pi5
Orionis. Finder charts of different scales, a small-scale map, and other event
details are at http://www.asteroidoccultation.com/2019_10/1026_97_61872.htm ;
while an interactive Google map of the path is at
http://www.poyntsource.com/New/Google/20191026_61872.HTM . ;
There are some pre-point opportunities that will allow you to point your
telescope to the precise altitude and azimuth that the occultation star will be
during the occultation, including one with 5.4-mag. SAO 111590 (J2000 RA 4h
04.2m, Dec +02 deg. 50â) 56m 47s (56.8m, good enough) before the occultation;
then at the time of the occultation, the target star will be 7 arc min. north
of where SAO 111590 was. An earlier chance is with 5.1-mag. SAO 110291 (J2000
RA 2h 02.0m, Dec +02 deg. 46â) 2h 58m 35s (2h 58.6m, good enough) before the
occultation; then at the time of the occultation, the target star will be 8 arc
min. north of where SAO 110291 was. I wanted to try a small mobile deployment
for this occultation along AZ87 n. of Payson, but Iâm behind in many other
things, including analysis of our important Psyche occultations, so all Iâll
do is look for a possible satellite occultation from home. I hope that others
in the path might try it. If you have portable equipment and time, it would be
worth the trip to get into the path of this bright event. It would be great if
a couple of others, preferably a little younger than me, could learn to use our
portable equipment for occasions like this.
_ _ _
2019 OCT 31, (351) YRSA: Then, on October 31 (yes, itâs Halloween evening),
at 7:28pm MST in AZ (Tucson region) and 8:29pm MDT in NM (Socorro region;
thatâs 2h UT of Nov. 1 UT), there will be an occultation of 9.5-mag. SAO
188092 (= TYC 6880-00768-1, spectral type K0) in eastern Sagittarius by the
41-km asteroid (351) Yrsa for up to 2s with a strong 6-mag. drop. In the
Phoenix area, the altitude will be 22 deg. in the southwest (azimuth 213 deg.),
but it will be close to that across AZ (including the path area over and s. of
Tucson), and a few deg. lower in central NM. The target star is at J2000 RA 19h
24m 55.9s, Dec -26 deg. 01' 31", 7 deg. southeast of Saturn and 1.5 deg. south
of 5.0-mag. chi1 Sagittarii. Finder charts of different scales, a small-scale
map, and other event details are at
http://www.asteroidoccultation.com/2019_11/1101_351_62890.htm while an ;
interactive Google map of the path is at
http://www.poyntsource.com/New/Google/20191101_62890.HTM . Iâll give ;
pre-point information in a later message.
_ _ _
PSYCHE OCCULTATION FIRST RESULTS: Joan and I set up and pre-pointed six remote
stations for the Oct. 23/24 Psyche occultation; they all recorded the event. At
least six other observers recorded the occultation from intermediate locations
across the path, so it should be possible to derive a good profile from the
observations For our effort, three were near each limit, with one only 2-3s at
the s. limit (our Sta. 1) and a 3s event near the n. limit (our Sta. 7; station
4 at Fountain Hills had to be dropped because the Sun, at nearly the same dec.
as the target, would have fried the telescope and camera). Stations 1-3 (the
southern stations) were pre-pointed on paver stones the night before, with Dale
Stanbridge managing the southern 2 on event night, and Claude Haynes taking
care of the 3rd one next to GRCO. Somehow, that Sta. 3 one was mis-pointed,
such that the target star disappeared just before it drifted out of the FOV, so
the R there was missed. But all of the others were pointed well enough to
easily record both events. Two of our northern stations used 80mm scopes; with
16x and Watec cameras, they easily recorded the occultation (we should have
used 8x with them for better timing). We tried to run a station 8 farther
north, but we probably didn't get on target there (only had about 20 min. and
had some trouble with the scope, which we could have taken care of if we have
brought a pair of pliers), but that station, just east of Kingman, probably had
a miss.
_ _ _
OTHER OCCULTATIONS: Besides these bright occultations, there are also some
faint ones observable with larger telescopes. On Sat. evening at 6:25pm, the
large asteroid (49) Pales will occult a 14.8-mag. star in Sagittarius for up to
5s, with a 0.4-mag. drop since the asteroid is a little brighter than the star.
Phoenix, Tucson, Albuquerque, and Socorro are all within the wide path; in
Phoenix, the star alt. will be 25 deg. in the southwest (azimuth 214 deg.)
while the Sun will be 10 deg. below the horizon. On Sunday evening at 11:07pm
MST, another large asteroid, (345) Tercidina, will occult a 12.7-mag. star in
Capricornus for up to 6s, with a good 1.2-mag. drop. The n. limit passes just
s. of Los Angeles, near Riverside, Prescott, and Albuquerque, while the s.
limit is just n. of San Diego (but with path uncertainties, an event could
occur there), Phoenix, and Socorro; ; in Phoenix, the star alt. will be 14 deg.
in the west (azimuth 249 deg.). Information about other occultations through
November can be found at http://iota.jhuapl.edu/AZoccs.htm . ;
David Dunham, dunham@xxxxxxxxxxxxx , 301-526-559
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