An Annular Solar Eclipse event happening right here in Singapore! (26th Dec 2019)

[rcj]

W i t n e s s . All are invited.



NEW UPDATES: Annular Solar Eclipse Official Event in Singapore (26 Dec 2019)!! ADMISSION IS FREE!

It is hardly just two weeks away from ECLIPSE DAY! Here are some updates to the public eclipse event held at Marina Barrage:
- Exact viewing site will be at the Marina Barrage Green Roof B.
- Food and beverages stalls will be on-site so everyone can have a really great time both astronomically, and gastronomically!
- As the event is really for the public, families, and friends, there will be fringe activities specially lined up for everyone, including terrarium-making, photography workshops, digital astrophotography showcase, eclipse information display, and more! Do get all your friends and families to come!
- In conjunction with ActiveSG, there will be a nice casual walk through Meadows by the Bay (near the exit from Bayfront MRT) to Marina Barrage Courtyard earlier in the morning (10AM).
- The eclipse event at Marina Barrage will officially commence from 10:30AM but you are highly encouraged to come earlier if you have instruments, and also yearning for a better car parking lot.

Looking forward to seeing everyone at the Marina Barrage eclipse event! We would like to thank all organizing support entities and volunteers that has and will be putting some good hard work on making this happen for everyone! So the rains must go away! Shoo!!


Stats (all times in local SG time):
GEOGRAPHIC COORDINATES OF MARINA BARRAGE ROOF B: 1.280698N 103.871077E
MAXIMUM MAGNITUDE - 0.97292
DURATION - 2m 11.4s
MOON/SUN SIZE RATIO - 0.96997
DELTA T - 69.4s
SUN AT GREATEST ECLIPSE (RA): 18H17M56.6S
SUN AT GREATEST ECLIPSE (DEC): -23.372027778DEG
MAX WIDTH OF BAND: 118KM

START OF PARTIAL ECLIPSE (1st Contact): 11:27:09.6AM (ALT:55.8, AZI: 137.6)
START OF CENTRAL ECLIPSE (2nd Contact): 1:22:40.4PM (ALT: 65.0, AZI: 189.8)
MID ECLIPSE: 1:23:46.0PM (ALT: 64.9, AZI: 190.3)
END OF CENTRAL ECLIPSE (3rd Contact): 1:24:51.8PM (ALT: 64.9, AZI: 190.9)
END OF PARTIAL ECLIPSE (4th Contact): 3:18:29.3PM (ALT: 49.2, AZI: 230.7)

What is an annular solar eclipse?

An annular solar eclipse will occur when the moon is far from Earth on its monthly elliptical monthly orbit. This results in the moon appearing to be smaller in the sky than the Sun. Therefore, when the conditions are right for an eclipse to happen, the moon will only cover the center of our Sun. It will begin with a partial solar eclipse for a few hours, and then it peaks as a circle around the moon, and it's therefore known as a "ring of fire" eclipse! What makes an annular solar eclipse very different from a total solar eclipse is that you MUST always wear protective solar eclipse glasses to view the entire event (at a total solar eclipse, observers can remove their solar eclipse glasses during the short totality). During an annular solar eclipse, the solar corona never becomes visible. However, they are still great to watch and experience. Any kind of eclipse is worth knowing about; if you're planning a vacation to any of the locations in the path (like coming to Singapore), it makes sense to delay/bring forward that trip to coincide with an eclipse, and together with the festive season!

Next Annular Solar Eclipse will be on 21 June 2020 (viewable from China)

[Airconvent]

Great Remus! If we can conduct another one to catch Jupiter and Saturn before the set, would be great too..

[rcj]

For those who are keen to capture the upcoming annular solar eclipse with your digital cameras and telescope (best to use a refractor or a telephoto lens), there will be two popular questions that you will want answers to:

1) How big the sun during the eclipse will be in your field of view (FOV) of your lens/telescope-camera setup, or perhaps for a given good sun size in your FOV, what key parameters pertaining to focal length / ratio you should have.

2) What exposure settings (exposure duration and ISO) to use.

First and foremost, we will need to consider the sun's diameter. That will be 32'31" = 1951" on Dec 26 1:17PM during the maximum annular eclipse moment for case of the southern part of Singapore.

Next, we use the formula:

F = 206.265 x S x U / T

Where:
S = size of the object in pixels as captured
U = pixel size of the camera in microns
O = true size of the Sun in arc-seconds
F = focal length as calculated from this formula, in mm.

Example 1: Assume using the Sony A7S with resolution of 4240 x 2832 (12MP) with 8.4 microns pixel size.

F = 206.265 x 2000 x 8.4 / 1951 = 1776mm

So if a 80mm aperture refractor is used, the effective focal ratio would be 1776/80 = f22.2

Example 2: Or if you want to check how big the sun will appear to be on your scope-cam combination for a given focal length say F = 1000mm, calculating in reverse will be:

1000 = 206.265 x S x 8.4 / 1951 which will give S to be 1126 pixels across or about 1/3 the height of your fov.

Next, in order to figure out the optimal exposure time and settings of annularity, we use the following formula:

t = (fr x fr) / (I x 2 power Q)

Where:
t = exposure time in seconds
fr = focal ratio
I = ISO speed
Q = brightness exponent

Take note that the exposure time derived above using the formula is based on optimal clear skies conditions, so it is wise to bracket your exposures 2-4 stops to take into account sky condition variance (cloud/haze, etc).

So if we base the scenario from Example 1 with fr = 22.2, I = 200, and Q at annularity is around 10-11:

For Q = 10,
t = (22.2 x 22.2) / (200 x 2 power 10) = 0.0024 seconds or about 1/500 sec.

For Q = 11,
t = (22.2 x 22.2) / (200 x 2 power 11) = 0.0012 seconds or about 1/1000 sec.

So in essence, if you are using an 80mm refractor operating at f20 or so, bracket your exposures for 1/500 to 1/1000 range for ISO200, or on the safe side, 1/250 to 1/1000 since it may be cloudy oh!

[rcj]

[Hardwarezone]

poster date typo 29 ????

[rcj]

thanks for pointing out!

[rcj]

amended the date already. see you all!

[Hardwarezone]

coverage by CNA