Check the NASA GSFC site for Live Stream Coverage of the Venus Transit from various locations around the world. You can select a location by clicking the markers on the map. There is also a link to NASA's Observing Challenge on this page.
Friday, June 1, 2012
Wednesday, May 30, 2012
Tuesday's Weather - NASA Coverage
The wunderground.com forecast for Fresno, CA says that there will be 34% overcast next Tuesday so it looks like it will be wait and see for a while.
The NASA TV Daily Schedule indicates that there will be some coverage of the Venus Transit but it is tagged TBD (to be determined). There is a 60% chance of rain in Mauna Kea with an indicated 0% cloud cover for next Tuesday. The time zone in Hawaii is HAST which is UTC - 10 hrs.
Venus Transit Subsolar Point
The picture of the Venus Transit shown in the map in the Wikipedia article is somewhat misleading due to the map projection. One can use MICA to determine the subsolar point for midtransit.
Ploting the midtransit subsolar point on a Google map showing the hemisphere where the Sun is visible gives the following result.
This gives a better picture of where the Venus Transit will be visible from. Note that the transit will also be visible from a good portion of the land bordering the Artic Ocean weather permitting. Throughout the transit the declination of the subsolar point is essentially constant and it moves along the same latitude as the Earth rotates.
Tuesday, May 29, 2012
Transit of Venus in One Week
As mentioned before the Transit of Venus will occur one week from today on Jun 5th or 6th depending on which side of the International Date Line you are on. It will be best observed in time zone UT + 10 hours which runs through Eastern Australia. One should be able to see the silhouette of Venus on the Sun's surface quite easily using eyepiece projection as one would do to observe sunspots. The entire transit will be observable in Australia and Eastern Asia after sunrise on the 6th. MICA details for Austrailia are shown in the image below. Note that the times are given in UT1 and can be converted to local time and correct for daylight savings time.
The entire transit will also be visible from Hawaii.
On the west coast of North America sunset will prevent the end of the transit from being seen.
If one does not have a telescope one should be able to see the transit on images of the Sun taken at Big Bear which are regularly updated. The transit may also be streamed live online from Hawaii.
Monday, May 21, 2012
Synchronizing Clocks & Network Time Protocol
Time displayed on the NIST time widget is seen to agree with the file's Modified time given in MS Office Picture Manager in the image below that was used to sychronize the camera's clock with the official time. So the best procedure may be to synchronize these two times.
The times used can vary by a second or two. Network Time Protocol is used to synchronize clocks over the internet. W32Time is used by some Windows computers to set the System Time for the computer. NISTIME 32 appears to use this method. The time zones are based on Universal Time (UT) which is adjusted periodically to maintain a correspondence with the Earth's rotation. The error is known as ΔT. We are due for a correction to UT1 in about a month from now on Jun 30. The times given by MICA for the eclipse use UT1. This may be a partial explanation for the problems encountered.
Above is a comparison of some of the times obtained by different methods showing a range of values. The times shown will depend on the time the image is captured.
Maximum Eclipse May 20, 2012
The following is an image captured near the time of maximum eclipse in Fresno, California at 6:34:00 pm.
The image is orientated with up corresponding to the local zenith. As one follows the Sun along the local azimuth the vertical changes.
The image above is one of the better images in terms of detail. The breeze tended to cause the telescope to rock back and forth which made capturing an image difficult. It was taken at 5:39:06 pm.
Supplemental (May 21): Google does not appear to be uploading EXIF image info any more. MS Office Picture Manager indicates two times for an image, a "Modified" time in "Picture properties" and a "Date Taken" in "Camera properties". The "Modified" time was 1 second earlier and is probably the one that agrees with the time shown on the NIST widget.
The image is orientated with up corresponding to the local zenith. As one follows the Sun along the local azimuth the vertical changes.
The image above is one of the better images in terms of detail. The breeze tended to cause the telescope to rock back and forth which made capturing an image difficult. It was taken at 5:39:06 pm.
Supplemental (May 21): Google does not appear to be uploading EXIF image info any more. MS Office Picture Manager indicates two times for an image, a "Modified" time in "Picture properties" and a "Date Taken" in "Camera properties". The "Modified" time was 1 second earlier and is probably the one that agrees with the time shown on the NIST widget.
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