Mid-Atlantic (& Mid-West) Occultations, 2014 August - October

David Dunham

• 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

A conference on planning for the 2017 August total solar eclipse, held on the3rd 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.

Occultations of faint stars by 49 Pales on Aug. 23 and by 39 Laetitia on Aug. 25 were also recorded from Columbia; Laetitia waspositive; Pales star probably too faint for me.

With the 56 alt., I needed to make Ted Blank’s tensioner mod for the 4 120mm refractor “AZ4”mounts that I brought.

Shorter dowels (white wooden cylinder; I spray-painted mineblack) were used

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 thesesites 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

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.

Dew compromised the sta.5 maxi observation, and was also present in varyingdegrees at sta. 1 – 4. The mount failed at Columbia;when she got up to turn onthe recorder there, thescope pointed straight up.

A conference on planning for the 2017 August total solar eclipse, held on the3rd 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, closestto 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 occultationobservation fits the orbit of Gorgoneion very well. The moon’sorbit is known, but not the position in the orbit, but IMCCE foundthat the new point is consistent with earlier observations. The position of the outer satellite Aegis is shown but its occultation was not observed. Messner’schord is 6.5 km, largerthan 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, wereIn 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.

Diagram adopted from skyandtelescope.com.

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.

Duration almost 40s (actually, about 35s) at Westford, MA; central was 58s.

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 Satellite/ dur. Ap. Date Day EDT Star mag. 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,ePASep 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 SCOct 2 Thu 22:53 2UC23239021 12.2 Hera 0.9 5 8 VA,DC,eMD,DE,sNJ_______________________________________________

Lunar Grazing Occultations2014 Date Day EDT Star Mag % alt CA Location & Remarks

Oct 1 Wed 21:21 SAO 161825 8.3 52+ 25 8S *Hamltn,VA;MtAiry&Finksbrg,MDOct 12 Sun 1:04 SAO 93927 7.5 83- 44 8N Chrltsv,Qantco,VA;Brndywin,MDOct 14 Tue 6:42 ZC 975 6.8 63- 66 3S Scotland,Loganville,PA;Sun -7

Interactive detailed maps at http://www.timerson.net/IOTA/

Upcoming Events for Central Maryland

Total Lunar Occultations2014 Date Day EDT Ph Star Mag % alt CA Sp. Notes

Oct 1 Wed 21:28 D SAO 161834 7.5 52+ 25 28N B2 Mag2 8.7,sep. ".4,PA154Oct 1 Wed 21:37 D ZC 2731 6.6 52+ 23 54S A1 close dbl, mag2 7.8Oct 1 Wed 21:44 D SAO 161850 7.2 52+ 23 43S A2 Mg2 13, sep. 10",PA 150Oct 4 Sat 1:04 D ZC 3051 6.9 76+ 14 54S K4 Azimuth 239 deg.Oct 4 Sat 18:46 D ZC 3169 6.1 83+ 24 15S K0 Sun alt. -1 deg.Oct 5 Sun 1:22 D ZC 3199 6.5 85+ 24 55N K0 Oct 5 Sun 22:14 D LP Aqr 6.4 92+ 45 13N M0 close dbl,ZC3328,TmD 9"Oct 6 Mon 18:51 D 14 Psc 5.9 97+ 13 86S A2 Sun -3, Az. 102, ZC3474Oct 11 Sat 23:38 R 63 Tauri 5.6 83- 28 7S A1 ZC 650, Term. Dist. 9"Oct 13 Mon 5:29 R 115 Tauri 5.4 73- 69 39S B5 ZC 814, close doubleOct 13 Mon 6:53 R ZC 823 6.7 73- 60 33N A2 Sun -5,Mag2 10,3",PA129Oct 14 Tue 1:47 R ZC 944 5.9 64- 33 85N A6 close equal dbl, "0.5Oct 14 Tue 6:20 R ZC 970 6.3 63- 68 65S G9 Sun alt. -12 deg.

Explanations & more information is at http://iota.jhuapl.edu/exped.htm .David Dunham, dunham@starpower.net, phone 301-526-5590