Tag Archives: Occultation

IOTA Announcement – Occultation By Neptune’s Moon Triton – 5 October 2017

Greetings, fellow astrophiles!

The following recently came across the ASRAS email list from ASRAS and IOTA member Brad Timerson. If you’ve the gear for it, this is an excellent chance to contribute to some far-out science.

There will be an occultation of a 12.5-mag. star by Neptune’s large satellite Triton the early evening of October 5th (just before 8pm EDT) that will be visible from east of the Appalachian Mountains. It’s the brightest star to be occulted by Triton since the Voyager flyby showed that the satellite has a substantial atmosphere with interesting dark plumes. The occultation will allow us to learn more about the atmosphere, and its variation with altitude and latitude. Sofia plans to fly over the Atlantic, to try to catch the central flash, where Triton’s whole atmosphere will focus/amplify the star’s light, probing deeper parts of the atmosphere. This might also be observed from Florida, but observations anywhere from the East Coast area are sought, to sample a wide range of latitudes of Triton’s atmosphere. Details of the occultation are available at MIT’s Web site for the event at hubble.mit.edu/prediction.html.

The central time for the Rochester area is within several seconds of 7:55:40 pm EDT on October 5th. For an observer near the center of the path, the event could last as long as 3 minutes. Because the Rochester area is north of that path, any occultation or atmospheric dimming would likely last some fraction of that time. You should plan to record the event for about 10 minutes before and after the time shown here.

A main challenge of the event will be to record Triton and the target star with a good signal, preferably with clear separation between 8th-mag. Neptune less than a quarter arc minute away. You will need good scale to separate the objects well enough. More observing tips are given on the MIT web site. The target star is about a magnitude brighter than Triton.

Telescopes as small as 8″ Newtonians will show the target star. (see included image from a European observer) For occultation work, we don’t need to “see” the occulting body (Triton in this case), just the object being occulted. Low light and/or integrating video cameras are best for this observation. However, standard astronomical cameras operated in a mode so as to produce images as quickly as possible will also work. Testing ahead of time to determine the correct exposure to just barely detect Triton should be done. This is to insure that the light from nearby Neptune doesn’t overwhelm that of the nearby moon and star at the time of the event.

Target star, Neptune, and Triton.

I plan on using my 10″ Meade LX200GPS at either f/6.3 (focal reducer) or at the normal f/10 prime focus. I will be using a Watec 120N+ low light video camera and integrating for 64 or 128 frames (2 seconds and 4 seconds). I’m still experimenting and might even need longer integration times.

Triton occults 4UC 410-143659, 5 October 2017 – visible regions from Earth.

Everyone with suitable equipment is encouraged to try this event. And I would appreciate it if this message is forwarded to any nearby universities that might have the ability to observe this event. If individual images are taken (instead of video) the exact time for each exposure is required (don’t depend on the computer’s internal clock. Use a GPS-based time). For analysis, it may be possible to measure the light level on individual images or the images can be combined into a video and measuring software used on the video.

Please contact me (EMAIL) for additional information or to submit observations.

5 March 2017 Aldebaran Grazing Occultation – Combined Videos On vimeo.com

Greetings, fellow astrophiles!

The following came across my email not to long ago from Brad Timerson of ASRAS and the IOTA, featuring the combined efforts of a number of members from the North York Astronomical Association. Five videos of the Aldebaran occultation this past March (posted about on the CNYO website HERE) were aligned and combined by vimeo contributor Andreas Gada into an amazing sequence that shows just how different the occultation looked even for six groups of observers lined up on the same road way up in Mississauga, Ontario.

Direct link to the vimeo: Aldebaran Grazing Occultation March 5, 2017 Combined Videos

Aldebaran Grazing Occultation March 5, 2017 Combined Videos from Andreas Gada on Vimeo.

Video Description: On March 5, 2017 a grazing occultation of Aldebaran occurred. To observe and image this event the North York Astronomical Association organized an outing to Mississauga Ontario. Ten people set up their equipment on Lionhead Golf Road. This movie combines the videos obtained to create a stereophonic visual account of this dynamic event.

Andreas also put together a video combining his own recording station with light curve data from Brad. That video, “Aldebaran Grazing Occultation March 5, 2017,” can be found at: vimeo.com/209855792.

Aldebaran Grazing Occultation March 5, 2017 from Andreas Gada on Vimeo.

The event page itself can be found at:
asteroidoccultation.com/observations/AldebaranGraze_05March2017/

Observing Announcement: Spectacular Grazing Occultation Of Aldebaran On 4 March 2017

Greetings, fellow astrophiles!

The following came in from Brad Timerson of ASRAS and the International Occultation Timing Association (IOTA). We had a few posts back in 2014 about an occultation of the star Regulus by asteroid Erigone (on what turned out to be an overcast March 20th. For information about the event and the observing process, see the original CNYO occultation post.

Local observing path for the lunar occultation of Aldebaran on March 4th.

Folks in Rochester and between Syracuse and Binghamton are ideally placed to not only observe the occultation, but also to take data to provide to the IOTA. Information about the occultation, including links to how you can help with the observations, is provided in Brad’s original email below:

I want to alert the membership about this great opportunity (if the weather cooperates!) of seeing a lunar grazing occultation involving a bright star, Aldebaran, along the northern edge of the nearly first quarter moon on the evening of March 4, 2017. In small telescopes, it should be a spectacular sight.

IOTA (International Occultation and Timing Assoc.) has prepared a webpage outlining this event. If you scroll down the page, you will find a section for the Rochester area with a couple of static maps as well as a Google Map for the area. Graze events are dependent on distance from the predicted graze limit as well elevation above sea level. So, the Google Map has been created for the elevation in the Rochester area. (100 feet either way makes little difference)

Main webpage for event: occultations.org/aldebaran/2017march/

Direct link to Google map for approximate elevation in Rochester area: occultations.org/wp/wp-content/uploads/2016/12/500ft.htm

Zoom in to see path through your area. Set the line A to a value of +0.2 km (enter value in box and then press “Click here”). Set line B to –0.1 km. This will produce 2 gray lines, one just north and one just south of the green line. These 2 lines (with the green line in the middle) will mark the best locations for an observing site.

A grazing informational image from the IOTA page.

Based on recent grazes, it appears that you will want to be exactly on the green line shown on the Google map or just barely south of it to see the maximum number of events. Many of the events will be gradual or partial (the star not completely disappearing) because Aldebaran is a large star and at the moon’s distance, won’t be completely covered for some locations.

I plan on observing the graze from a store parking lot (after getting permission) along Rt. 96 near Clifton Springs, NY. Anyone near this area is welcome to join me. I will have more details on my location as the date approaches. I will be videotaping the event using a special camera and video time inserter so that important details of the lunar limb and, possibly, the star, can be determined.

Profile maps of the Aldebaran occultation from the IOTA page.

Central graze time for the Rochester area is 11:17:57 pm on the 4th. You’ll want to be setup well ahead of this time with a clear western horizon. The moon will be about 18° above the horizon. You may see events occur for up to a minute before and after this central graze time. Below is a profile of the lunar limb showing the predicted graze limit as well as a dotted line at about 0.2 km south of the limit. The gray bar graph at the left shows the number of events that can be expected to occur. Time is along the bottom with 11:17:57 pm centered.

Please email me individually (btimerson [_at symbol_] rochester.rr.com) if you’d like information about a specific site along the graze path. Include the latitude, longitude, and elevation of your site taken from Google Earth of the Google map. Also, any other questions you might have can be directed my way.

Here are links to the pages summarizing observations made at the last two grazes. Many observations have YouTube videos available so you can see what to expect.

* www.asteroidoccultation.com/observations/AldebaranGraze_29July2016/
* www.asteroidoccultation.com/observations/AldebaranGraze_19October2016/

Brad Timerson
Newark, NY