Transcript 2014sep_occultations

Mid-Atlantic (& Mid-West) Occultations,
2014 August - October
David Dunham
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August 24th (393) Lampetia occultation, Missouri
Sept. 6th (93) Minerva (& sat.) occultation, Minn.
Sept. 12/13th occ’n by Saturn’s Rhea, N.E. USA
Upcoming occultations
• http://iota.jhuapl.edu/exped.htm
Occultations of faint stars by 49 Pales on
Aug. 23 and by 39 Laetitia on Aug. 25 were
also recorded from Columbia; Laetitia was
positive; Pales star probably too faint for me.
A conference on planning for the 2017 August total solar eclipse, held on the
3rd anti-anniversary of that event at the Univ. of Missouri in Columbia (near
the central line of the 2017 eclipse), provided an excuse to try to observe this
Sunday morning event from north-central Missouri. Also, we stayed with my
brother-in-law, who works at the Univ. of Missouri.
Shorter dowels
(white wooden
cylinder; I spraypainted mine
black) were used
With the 56 alt., I needed to
make Ted Blank’s tensioner mod
for the 4 120mm refractor “AZ4”
mounts that I brought.
Planned Remote Stations 1 – 3 north of Columbia
The blue line is the predicted southern limit. My brother-in-law, Jim Bixby, helped me set
up these three stations, and returned to them to attach and turn on the camcorders, and
picked up the equipment afterwards. Joan tried to observe from Columbia.
Station 1 was most difficult, in high grass/bushes to hide the scope
The poison ivy I got setting up the scope there is almost gone now.
Planned Remote Stations 4 – 6 farther north
The green line is the predicted center, the blue line is the predicted northern limit, and the
red line is the “1-” n. limit. I ran out of time and didn’t make it to the northernmost of these
sites but had time to set up the 6th site 2 miles south of the bottom one in Macon, MO.
So far, only Stations 5 & 6 near the central line have been analyzed
Dew compromised the sta.
5 maxi observation, and
was also present in varying
degrees at sta. 1 – 4. The
mount failed at Columbia;
when she got up to turn on
the recorder there, the
scope pointed straight up.
There is an error in the times for chord 4 (my station 5) in this plot; chord 6 (my station 6; it was dry)
is correct. With job obligations & the next 2 better events, I haven’t had time to work more on this.
A conference on planning for the 2017 August total solar eclipse, held on the
3rd anti-anniversary of that event at the Univ. of Missouri in Columbia (near
the central line of the 2017 eclipse), provided an excuse to try to observe this
Sunday morning event from north-central Missouri. Also, we stayed with my
brother-in-law, who works at the Univ. of Missouri.
The target star was near 5th-mag. 41 Tauri, and not far from the Pleiades.
6 Stations Planned, & Set Up, near I-94 from St. Cloud to Fergus Falls, MN
Predicted lines are: Red, 1- eastern limit; blue, eastern limit; & green, central line.
In the lower left are two stations planned (and also successful) by Steve Messner from
Northfied, MN (his sites were at/near a camp ground on SD border). Farther to the northwest,
Paul Maley, with help from students at a local university, set up 4 stations around Fargo, ND to
cover the western part of the path. Bob Sandy tried in Nebraska, but was clouded out.
All stations for the Minerva occultation;
north is towards upper-upper-left
Predicted lines are: Red, 1- eastern limit; blue, eastern limit; & green, central line.
Predicted lines: Green, center; Blue, limits; Red, 1-sigma limits.
A good distribution, but the actual path shifted a little west.
Red dots had no occultation; Green dots had an occultation.
A sky-plane plot showing the paths for all stations; our 3 eastern
stations had no occultation (chords 13 -15). Joan assisted me all night.
There is an error in the times for chord 4 (my station 5) in this plot; chord 6 (my station 6)
is correct. With job obligations & the next 2 better events, I haven’t had time to work more on this.
The observations fit Minerva’s shape model very well.
Light Curve from Steve Messner’s campground remote station, closest
to the predicted central line – “A lucky hit”
The blue dots are for the taret star; the count at the bottom is in video frames (each 1/30th sec.).
The green line in the middle is a comparison star in the FOV that was not occulted.
The thick red vertical lines mark the D and R by Minerva. But notice 20s after the main event,
there is another brief drop lasting 0.6 seconds. This turned out to be an occultation by Minerva’s
inner moon, Gorgoneion.
An expanded view showing the Gorgoneion event in the lower right.
This plot by Frédéric Vachier, IMCCE, Paris, shows that Steve Messner’s
secondary occultation
observation fits the
orbit of Gorgoneion
very well. The moon’s
orbit is known, but not
the position in the
orbit, but IMCCE found
that the new point is
consistent with earlier
observations. The
position of the outer
satellite Aegis is shown
but its occultation was
not observed. Messner’s
chord is 6.5 km, larger
than the expected 3.2
km size expected from
the earlier data.
HIP 74007 = SAO 159034
Expanded view showing States
The predicted northern (red) and southern (blue) limits are highlighted.
The sky was too bright to observe west of the Mississippi River.
Saturn was low in the southwest
Saturn, Mars, and Antares, all orange and nearly the same brightness, were
In a line at about the same altitude, with Saturn on the right.
The 7.8-mag. star was 1 arc minute east of Saturn, with Titan below it.
Diagram adopted from skyandtelescope.com.
25h Transparency Forecast poor for MD; NJ looks best in Mid-Atlantic Region
13h Transparency Forecast better for MD, but NJ is farthest from the clouds
So we went to NJ, and Ernie Iverson in TX looked at sat. images to try to guide us
IR satellite image close to the Rhea occultation time
Steve Conard got the best light curve with his C14 at Willow Oaks Obs.
The Duration was 16.4s at Gamber, MD.
At Greenbelt, MD, it was 9.3s, while at
the US Naval Obs. in DC, it was 7.8s.
Conard’s S/N was 7.0; the next best was 1.8.
In NJ, I had 22.8s, S/N 0.8 through thin clouds.
40s (actually, about 35s) at Westford, MA; central was 58s.
DiagramDuration
adoptedalmost
from skyandtelescope.com.
Sky-plane plot of the 2014 Sept. 12/13 Rhea observed chords
The shortest chord, #9 at the US Naval Obs., was 7.8s; B. Huxtable in s. Del. had a close miss.
Upcoming Events for Central Maryland
Asteroidal Occultations
2014
Date
Day
EDT
Star
mag.
Satellite/
dur. Ap.
Asteroid dmag s " Location
Sep 18 Thu 20:34 4UC444130878 14.5 Chiron
4.2 12 12 Cuba; e. USA?
Sep 30 Tue 1:40 2UC42900457 12.5 Terpsichore 0.9 9 8 w&nVA,DC,MD,ePA
Sep 30 Tue 2:32 TYC01420016 11.2 Spiridonia 4.6 4 7 OH,MD,NJ;DC,nVA?
Oct 1 Wed 23:00 TYC62662813 10.8C Laetitia
0.4 12 9 All MidAt,not SC
Oct 2 Thu 22:53 2UC23239021 12.2 Hera
0.9 5 8 VA,DC,eMD,DE,sNJ
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Lunar Grazing Occultations
2014
Date
Day
EDT
Star
Mag
% alt
Oct 1 Wed 21:21 SAO 161825 8.3 52+ 25
Oct 12 Sun 1:04 SAO 93927 7.5 83- 44
Oct 14 Tue 6:42 ZC 975
6.8 63- 66
CA Location & Remarks
8S *Hamltn,VA;MtAiry&Finksbrg,MD
8N Chrltsv,Qantco,VA;Brndywin,MD
3S Scotland,Loganville,PA;Sun -7
Interactive detailed maps at http://www.timerson.net/IOTA/
Upcoming Events for Central Maryland
Total Lunar Occultations
2014
Date
Oct
Oct
Oct
Oct
Oct
Oct
Oct
Oct
Oct
Oct
Oct
Oct
Oct
1
1
1
4
4
5
5
6
11
13
13
14
14
Day
EDT
Wed
Wed
Wed
Sat
Sat
Sun
Sun
Mon
Sat
Mon
Mon
Tue
Tue
21:28
21:37
21:44
1:04
18:46
1:22
22:14
18:51
23:38
5:29
6:53
1:47
6:20
Ph Star
Mag
%
alt
D
D
D
D
D
D
D
D
R
R
R
R
R
7.5
6.6
7.2
6.9
6.1
6.5
6.4
5.9
5.6
5.4
6.7
5.9
6.3
52+
52+
52+
76+
83+
85+
92+
97+
8373736463-
25
23
23
14
24
24
45
13
28
69
60
33
68
SAO 161834
ZC 2731
SAO 161850
ZC 3051
ZC 3169
ZC 3199
LP Aqr
14 Psc
63 Tauri
115 Tauri
ZC 823
ZC 944
ZC 970
CA Sp. Notes
28N
54S
43S
54S
15S
55N
13N
86S
7S
39S
33N
85N
65S
B2
A1
A2
K4
K0
K0
M0
A2
A1
B5
A2
A6
G9
Mag2 8.7,sep. ".4,PA154
close dbl, mag2 7.8
Mg2 13, sep. 10",PA 150
Azimuth 239 deg.
Sun alt. -1 deg.
close dbl,ZC3328,TmD 9"
Sun -3, Az. 102, ZC3474
ZC 650, Term. Dist. 9"
ZC 814, close double
Sun -5,Mag2 10,3",PA129
close equal dbl, "0.5
Sun alt. -12 deg.
Explanations & more information is at http://iota.jhuapl.edu/exped.htm .
David Dunham, [email protected], phone 301-526-5590