July 18, 2016
Scanning Recommendation for Solar Drawings
Recent questions about what format drawings should be in when submitted to the Solar Archive, prompt us to write this post. Despite that many say that they want the highest quality and thus scans should be submitted in the highest possible resolution, this does not make a lot of sense. Drawings are made typically by pencil or a marker. In addition, the drawing should as accurately reflect what someone saw and document this accordingly. Think of it as this way: If you scan at 200 dpi (dots per inch) this means that the scanner will create a dot if it finds a line that is 1/200 of an inch or 1/8 of 1mm. So the question becomes can you draw features on a Solar disc and accurately position it to that scale? Without any further aid probably not. In addition, images are mostly available in the jpg format. This standard format allows a compression grade of 1 to 12 for the file data in the image, so the file becomes smaller in size. A full 8 1/2 by 11 sheet could take up 7 MB or larger when uncompressed, but compressed it might be only 250 – 300 kB. This is a huge difference if images need to be downloaded or processed.
So let’s take a look at how a PC does display images and data. A typical PC monitor is approx. 1250 pixels wide. Some are wider and others have less pixels available. So if you were to display the width of an 8 ½ x 11” paper across the width of the screen you would have 1250 pixels available and the screen is probably 13 to 15 inch wide. This would mean that if the page was displayed across the width of the entire screen, it displays at approx. 1 ½ times the size of the real sheet of paper and it would be displayed at a resolution of 1250/8 ½ or approx. 150 pixels per inch. This would be the optimum resolution for that screen to display that page. Images captured with the current technology also have a similar resolution of 1200 -1800 pixels wide. So increasing the resolution only makes the image bigger resulting in only a portion of that image being displayed on the screen and does not necessarily increase the clearness of what you did draw.
We have taken a good look at what the best format for our purpose is, and we have concluded the following: A scan with 150 to 200 dpi produces sufficient data to properly represent what’s on the paper you scanned for analysis, as well as reproduction in printed form. In addition, when the image is saved in the form of a jpg, a compression grade of 5 to 6 for the data compression, retains more than sufficient data to properly reconstruct what was scanned. This compression grade number is displayed in many programs when the file is saved as a jpg file, including Photoshop CS or PS Elements. So to summarize, for images to be submitted in our archive we prefer if you can scan drawings as follows:
Scan with 150 to 200 dpi.
Use jpg compression grade at 5 to 6 when saving the file.
This should produce files of reasonable size for on-line access. Remember, there are still many individuals who like to see your images, but they also have to deal with slow internet, or even dial up speeds.
Thanks for your consideration, and if you have any further questions or suggestions, please do not hesitate to send your question/suggestion to email@example.com .
The Solar Team.
July 10, 2016
A short Summary of Carrington Rotation 2178
Carrington Rotation 2178 covered the time period from 2016-06-06 – 0557 UT until 2016-07-03 – 1040 UT.
Submitted observations can be viewed in ALPO’s Solar Archive for CR2178:
CR2178 was the first rotation since the solar maximum that started with no reported Active Region and ended with no regions during the last 10 days. In fact only during 16 days, the Sun’s activity showed ARs and Sunspots. The total number of regions that could be observed was limited to 7. The largest Region AR2553 reached its maximum size at 330 millionths only three days after it emerged from the Eastern Limb, while the Sun’s total active regions maxed out the same day at 500 millionths. The largest number of Sunspots (12) were counted when AR2552 was the only region three days before.
Despite the low activity during the rotation, observers did submit 401 observations to the ALPO Solar archive. Thanks to all who observed the Sun for their dedication. Following are a few observations submitted by Dave Tyler, Howard Eskildsen and Theo Ramakers, including an “empty” Sun, but all submitted observations can be seen by following the link above.
Your Solar Section Team
June 17, 2016
ALPOSS – A report on CR2169 thru CR2173
ALPOSS’ Acting Coordinator and Scientific Advisor Richard Hill continues his detailed reports of the Carrington Rotations. This time he covers 5 Carrington Rotations: CR2169 thru CR2173. The reports are based on over 500 submissions of numerous contributors to the Solar Observations Archive. The report was published in the 2016 Summer issue of the JAPLO and can now also be accessed as a stand alone document on ALPOSS’ Solar Observations & Reports page, or downloading by “right”clicking on the picture below.
June 7, 2016
A short Summary of Carrington Rotation 2177
Carrington Rotation 2177 covered the time period from 2016-05-10 – 0053 UT until 2016-06-06 – 0557 UT
Submitted observations can be viewed in ALPO’s Solar Archive for CR2177:
11 Active regions could be observed during the period, which started with four active regions, an active region area total of 210 millionths, as well as 28 sunspots. The largest region was AR2546 which reached its maximum of 540 millionths on May 17th. The shortest lived Active Region was AR2547 with a duration of two days only and did not grow larger than 10 millionths. The active region total for the solar disk maxed out on May 16th at 770 millionths, one day before AR2546 reached its maximum. The highest number of Sunspots (37) could be observed on May 15th.
The last 7 days of the Rotation the Sun did not produce any C-class flares, and the last 5 days even went without any B-Class flares, resulting in an overall Very Low solar activity. To top it off, the Rotation ended with three days of no registered active regions or sunspots, a clear indication that we are on the way to the Solar minimum. At the end of the Rotation, observers had submitted 273 observations to the ALPO Solar archive. Thanks to all who observed the Sun for their dedication. Following are a few observations submitted by Tony Broxton, Avani Soares, and Monty Leventhal, but all submitted observations can be seen by following the link above.
The ALPO Solar Team.
May 20, 2016
Carrington Rotation 2176, a short summary
The Rotation ran from 2016-04-12 1857 UT till 2016-05-10 0053 UT.
Submitted images can be viewed at the following URL:
15 Active Regions could be observed during the rotation (AR2529 – AR2543). The rotation started with a total active region area of 880 millionths and 22 sunspots and ended with a total active region area of 210 and 28 spots. The largest region in the previous rotation, AR2529, continued to be the dominant region for this rotation too, and maxed out with an area of 850 millionths. The lowest total area was recorded on April 23rd with 70 millionths. It has been a while since the Sun produced a flare larger than a M5, However early morning 4/18 marks the day/time when it produced an M6.7 flare which did cause an R2 alert to be posted. The highest Wolf Number (86) was recorded for 4/28 with 6 regions and AR2535 showing 9 spots by itself, and the lowest Wolf Number (11) on 4/24 when only region AR2433 was observed with only one sunspot.
The last day of the rotation showed a special event, the Mercury transit which was the subject of the previous summary. The archive received over 380 submissions for the rotation, with an additional 40 for the Mercury transit.
Thanks to all who spend their time observing the Sun, and submitting their observations.
The ALPO- Solar team.
May 14, 2016
The Mercury Transit, a short summary
As of this writing the ALPO Solar Section received 26 submissions of observations of the Mercury Transit. The transit was well advertised in the JALPO and Solar blog through John Westfall’s article about the transit. In order to accommodate the request to provide a number of images taken exactly at the full hour, a number of submissions were filed which were taken to the second at XX.00 .00 UT. It is our understanding that some of these images have been used by individuals to re-calculate the distance between the Earth and the Sun ( 1 AU). In addition several composite images showed the planet as it tracked in front of the sun and during ingress and egress. Take a look at the archive to see what was submitted:
We’d like to thank all that took the time to observe this event and submit their observations.
The ALPO Solar team.
May 3, 2016
The Mercury Transit, a call for image submissions
Well, it is less than a week until the Mercury transit, and a group of individuals is looking forward to try, based on the parallax shown in images of the transit at the same time, when made from different locations from Earth, to calculate the distance between the Sun and Earth. In order for this to be successful they will need images made at the same time and know the exact coordinates of the location on Earth where the image was made. We are suggesting to not only submit your images of the transit, but if possible also an image of the full sun at exactly the full hour (if possible to the second because Mercury as well as the parallax are very small), so these enthusiasts will have data they can use. If you make an avi, please use the center time of the avi.
In addition, the ALPO’s Transit section will use the data for an extensive report to be published at a future date in the Stolling Astronomer, the Journal of the Association of Lunar and Planetary Observers (the ALPO).
We hope that Solar imagers will consider this request, and submit all their images (also partial Sun images and close ups) attached to an email with the exact time and coordinates of the location addressed to: firstname.lastname@example.org .
Thank you and wishing you all Clear Skies,
April 16, 2016
Carrington Rotation 2175, a short summary
Carrington Rotation CR2175 ran from 2016/03/16 11:58 UT until 2016-04-12 18:57 UT.
Submitted images and observations are archived here:
The rotation started with a total Active Region Area size of 140 millionths and a Wolf Number of 59. It ended with a total region size of 880 millionths, and a Wolf Number of 42. During the period, the Sun showed 11 Active Regions (AR2519 & AR2521 – AR2530) and it looked for a while that AR2524 would be the dominant region, until four days before the end of the rotation, when AR2529 came around the Eastern limb. The rotation maxed out as it finished on April 12th, when AR2529 had grown to a size of 850 millionths. However, AR2524 still managed to be a key contributor to the highest Wolf number of the rotation of 66 (5 regions and 16 spots) on March 18th. The largest flare, a C3.7, was produced by AR2521 on March 20th, just when it was getting ready to turn to the far side of the Sun.
We are showing three images below which were captured close to the key dates mentioned above. The images were submitted truly by a number of international contributors: Guilherme Grassmann from Brazil, David Tyler from the UK, and Gabriel Corban from Rumania.
As of this writing, ALPO received 226 observations/images for the rotation, and we like to thank all that took the time to submit their images/observations.
The ALPO Team.
April 6, 2016
Carrington Rotation 2174, a short summary
CR2174 ran from 2016-02-18 04:08 UT till 2016-03-16 11:58 UT. We received 222 images/observations for this rotation. This is the first time again since April 2011 that we were able to archive over 200 submissions for one rotation.
The rotation started with a total Active Region Area size of 300 millionths and a Wolf Number of 60. It ended with a total region size of 180 millionths, and a Wolf Number of 57. During the period, the Sun showed 22 Active Regions (AR2497 plus AR2501 – AR2522). The highest total Active Region Areas size was 300 on the first day of the rotation, which was mostly contributed to the size of 220 of AR2497, which was turning that day to the far side of the Sun. For the rest of the rotation, the total areas size maxed out for on February 26, at 260 millionths. The largest region during the rotation except for AR2497, was AR2505 which measured 180 millionths on February 22nd. The daily Wolf number reached its maximum on March 5th at 95, which was mainly caused by an increase of the number of areas for one day, rather than spots. The observations/images below, were submitted by Gabriel Corban, Dave Tyler and Howard Eskildsen.
Thanks to everyone for their contributions to the archive.
The ALPO team
March 30, 2016
The 2016 Mercury Transit
Have you already made any plans for the Mercury Transit which is coming upon us very fast? Dr. John E. Westfall, the Coordinator of the Venus and Mercury Section wrote a marvelous article in the Spring Journal of the ALPO about the transit which is to happen on May 9th. We are encouraging everyone to read this in order to become familiar with what to expect, and if you actually observe or image the event, we always appreciate your submissions for our archive via email to email@example.com .
In addition, those who might take on the challenge to calculate the length of the Astronomical Unit (distance between the Earth and the Sun), might research the Solar Section’s archive the days after the event to look for the right images captured by individuals separated far enough from each other to extract the data they need for this effort. Follow the link here to download Dr. Westfall’s article.