The Graze of ZC 1384 - Apr 19/20, 2013

ZC 1384 is a 7.2 mag star which may be a ~0.05" binary based on a gradual occultation event. The star grazes the northern limb of a 66% waxing gibbous moon on Friday evening at 10:15pm, from a path crossing near Fairfield and just north of Tracy. The profile promises more events than any human grazer could possibly handle, at 0.9 miles south of the elevation corrected limit. Here's the predictions


Derek's interactive map of the path.

Profile. The sweet spot is 0.96 mi South, or 1.54 km south. However, all sites between 0.91 and 1.05 miles south look about equal in their promise to supply a boat-load of events. The places providing the detail change over that range.

The central graze time is 5:19:15UT, or 10:19:15pm PDT

The Meeting Spot?:

Subway restaurant at 3400 MacArthur Dr and E. Pescadero. Meeting time is 8:00pm. Chris A and Chris K will plan to be there. I hope to get there in time and if not, just head to the site. My setup can happen quickly. Others - you could skip the Subway and just go straight to the graze site to maximize the time margin safety factor in setup.




This looks like a great graze site. On California Ave a half mile north of I-205. We set up along California Ave on the west side, where there is a level wide dirt area that allows us to pull our scopes and equipment completely away from traffic, and see the moon at azimuth 223 at altitude 53 degrees, very high up in the south west.

RN at 0.93s, CA at 0.97s, CLK at 0.99s, RB at 1.03s and I honestly can tell who'll get the most events. If anyone else comes, I would suggest they set up just north of me, but no farther than the intersection with Canal St.

A close up view of the graze road prime area.

It's 4.2 miles from the meeting spot at the Subway Restaurant, to the prime graze site, following this set of turns.

Site selection: Looks like we'll have 3 and maybe 4 . RN at 0.93s, CA at 0.97s, CLK at 0.99s, RB at 1.03s and I honestly can tell who'll get the most events. If anyone else comes, I would suggest they set up just north of me, but no farther than the intersection with Canal St.

Second Graze - magnitude 8.2 at 11:39pm from Dublin Canyon
From the end of the 7.2 mag graze to the beginning of this graze, is 1hr 15 minutes. The site would be right on the predicted limit, and there's a convenient spot on the frontage road Dublin Canyon Rd. It's about a 36 mile drive from graze site #1 to graze site #2, and so that gives little time for setup. I'm pretty fast with my setup, but Chris K will have more equipment and it might not be practical. Before too much more personal effort, I will wait for a go/no go from Chris. The star is 8.2 in V, but 7.4 in R so it has a later type spectrum and will show better than an 8.2 star might suggest. I'm sure it's easily do-able with my 10" and equipment. The profile is not as interesting, but may give a series of D's and R's for a 30 second period near the top of the profile, and which corresponds to the far right side mountains we aim at for the first graze, now tipped to the top of the profile. Only a very fast take-down and set-up and a drive-like-hell mentality has a hope of getting both grazes.

street view of graze site on Dublin Canyon Rd frontage to freeway
pullback view of graze site, west of Dublin


Post Graze Pix and Results

The Subway on Pescadero Rd in Tracy - fuel up for vehicles and drivers!

At Dr. Kitting's station; Chris, me, Robert before the graze

Chris K fine-tuning his rig. Got both PC164cEX2 data and also HD video through his Canon

Chris Angelos anchored the southern end of our tight graze line, next to the canal. A local drove by, offered a beer!

Robert did visual timings with radio/voice from his station, about 100 ft south of me.

I'd have welcomed a cold beer. Alas, just two barking dogs for me at my station. However, this photo is from the second graze of the night, a mag=8.2 star grazing from Dublin Canyon east of Hayward.

Chris got packed and arrived 10 minutes before the graze - not enough time to unpack and set up. But I was ready, and got 6 events before my tape ended. My "60 minute" tape was really a 57 minute tape. Found out the hard way.


After the grazes, Chris and I drove back to his place, examined our data, and got to sleep after 1am. Morning was delicious, with French Toast and fresh fruit out on the back lawn prepared by Shoko. Thanks to all for a memorable start to the weekend!