Stars over Yosemite

Information about the SJAA star party at Glacier Point,
Yosemite National park -- August 23-24, 2013

    The 2013 Yosemite star party has come and gone, with many good memories, despite having the moon rise part way through the star parties.

    The Milky Way was splended, sprawled across the sky from northeast, overhead, and ending to the south. At moonrise, there was little difference. As time went on, the Milky Way gradually faded, and was not seen about an hour after moonrise.

    It was also interesting to compare the scenery by moonlight, verses the daytime view. Though we knew what was near and what was far away, by moonlight it all seemed to be at the same distance. But moonlight is not bright enough to allow our eyes to see color! So we concluded that color is important in judging distance.

    The massive fire northwest of the park did not interfere with the star parties nor with enjoying the park, other than the closure of highway 120. We had no smoke in the valley nor over Glacier Point.

    We look forward to 2014!

    The annual Yosemite star party is held at Glacier Point. Camping space is at the Bridalveil Creek campground, about 9 miles from The Point. There is room for several tents. The camping is rough by modern standards: no dining room, no showers, no hot water. The camper limit is 30 feet, but that's really too big for the sites that we use; a van camper is much preferred.

    We are given free admission and camping space. In exchange, we are expected to set up our telescopes for both public star parties at Glacier Point, on Friday and Saturday night. If you have never set up for the public, this is definitely not the place to try it for the first time!

    We have the public (about 200 - 300 people) from twilight until about 11 pm, and then have the rest of the night to ourselves.

    For all these reasons, this is not suitable for a family camping trip.

    We may take a maximum of 30 people, with priority given to SJAA members. We are expected to have at least one public telescope for every two people. If you can tolerate the conditions outlined, write to Jim Van Nuland with the number of people and telescopes. If you would rather arrange your own housing, let Jim know that too, and how many telescopes you'll set up for the star party.

    Jim will mail the gate passes a few weeks before our weekend.

    The luck of the date raffle ran against us this year. The moon will be full on the previous Tuesday, so we'll have a bright moon rising in mid-evening. The rise times given below are calculated for a flat horizon, so we will not see the moon until perhaps 30 to 45 minutes after those times. But the air above Glacier Point is very clear, so the moon will not be as troublesome as it would be in San Jose.

    Be sure to put a dense filter into your telescope when showing the moon, so that people's vision will not be overwhelmed by moonlight, and would be unable to see afterward.

For those past the 30-person camping limit, or who will make their own arrangements at a motel:

    Yosemite is your park, and you are welcome come if you arrange your own accommodations. You would be welcome to join us at Glacier Point for the public star party and the general observing afterward.

    There are several motels in the community of Yosemite West, which is much nearer than the inns on the valley floor. Try googling on "Yosemite West".

    If you will set up a telescope, let Jim Van Nuland know that you are coming.

If you have not been to a Glacier Point star party before:

Download Gary's detailed directions, which include:
  • Directions via Hwy. 120 to Yosemite's Big Oak Flat (north) entrance, with maps and notes;
  • Details on the Bridalveil campground, with maps and photos;
  • Directions and information on the star party at Glacier Point;
  • Abbreviated version of the directions (easier to use while driving);
  • Notes on the trip back home.
In addition, peruse the FAQ page for various tips.

    When you arrive at Yosemite, make your way up to the Bridalveil Creek campground. Do not confuse it with the walk-in viewing area at Bridalveil Fall. From that area, the driving distance is 18 miles, uphill and twisty. Allow about an hour from the Fall parking lot, but make a stop at the Wawona Tunnel overlook, which is the classic view of Yosemite Valley. Try to reach the camp by 4 pm at the latest.

    At the campground, go to loop C, and find sites 81, 83, 85, 94, and 95, with "Reserved for Park Volunteers" on them. All are on the left side the road, along a long curve. The curve and sites enclose a large common area "behind" the sites, where tents can be set up.

    Note that sites 89 and 93 are not volunteer sites, even though they fall between the volunteer sites. We will try to buy them, but if they do not have "SJAA" or "JVN" on the number post, they are not ours.

    From the camp, Glacier Point is another 9 miles up the road. Allow time to find your way and set up; the summer sunset is late, so there's adequate time. We usually are setting up by 6:30, as we can bring in only a few vehicles at a time to unload, and they must quickly be returned to the parking lot, even before you set up.

    The observing area is partly open, with good views from about NNW to the east, around to due south. From south around past west is partly to mostly blocked by tall trees. Still, there's a lot of open sky, and typically, the seeing and transparency are excellent. It is typically warm (80 to 90) during the day, and cool to chilly (40) at night, due to the elevation, 7200 feet.

    On each evening, we may take a group picture about 10 minutes before sunset. Picture time will be 7:30 pm in 2013.

    One of the rangers does a sunset talk, and then delivers the crowd to us. Some will have flashlights, and we need to be tolerant of that. Pick out a show object that you are familiar with, tell about it, etc., just as we do at Houge Park and schools. Hopefully we'll be on different objects. Expect lots of questions. By 11 or so, we'll have the place to ourselves, and can stay until dawn.

    Scopes must be removed when we quit, then set up again on Saturday. We have two "leaving windows" (midnight and 3 am) to manage the lights associated with packing up. Please be considerate.

    Miscellaneous questions and answers are tossed onto the Yosemite FAQ page.

Sun and Moon data

    The Moon will be full on Tuesday, August 20. The moon will rise during the evening, partly cutting into what can be shown. But the air over Glacier Point is usually very clear, so the moon will not interfere as much as it does in the cities.

    The following times do not allow for the elevation or local horizon, so rise times will be late by about 25 minutes near east, and by about 45 minutes when the object is northeast or southeast. The error will be even larger when the object is behind a mountain peak.

                                                Aug. 23      Aug. 24    2013
                                                Friday       Saturday
                                   Moonset:      9:18 am      10:22 am
                                    azimuth:      276           282
                                   Sunset:       7:40          7:38
                                    azimuth:      285           284     behind the trees
                                   C-twilight:   8:07          8:06     Sun  6 degrees down
                                   N-twilight:   8:40          8:38         12  "
                                   A-twilight:   9:14          9:12         18  "

                                   Moonrise:     9:07 pm       9:42 pm
                                    azimuth:       81            76     Right of Half Dome
                                    illumination:  88%           80%
                                      ------- next ------- day -------
                                   A-twilight:   4:48 am       4:49 am  Sun 18 degrees down
                                   N-twilight:   5:22          5:23         12  "
                                   C-twilight:   5:55          5:56          6  "
                                   Sunrise:      6:22          6:23
                                    azimuth:       75            76

                                   Longitude:   119 deg   34.6 min
                                   Latitude:     37 deg   43.5 min
                                   Elevation:  7200 feet  WGS84

Pictures and links

Click picture for bigger version.
[Image: Team 2013 at Yosemite N.P.]
SJAA Team 2013 at Glacier Point, Yosemite National Park
[Image: Bear in Glacier Point parking lot]
An unwelcome guest. Bear in Glacier Point parking lot.
[Image: Bear entering lower observing area]
Bear entering near fire ring.
Do not bring any food into the observing area, not even sodas.

For 2006 pictures, go to Morris' Yosemite 2006 page.

To School home page. Mail to Jim Van Nuland.

Last updated: 2013 Sep 3, 1306 hours, PDT --
New picture of astronomers

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