Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

"Seeing"how?

  • Please log in to reply
6 replies to this topic

#1 Lite2

Lite2

    Mariner 2

  • -----
  • topic starter
  • Posts: 253
  • Joined: 18 Jan 2017
  • Loc: USA, Indiana

Posted 11 July 2018 - 11:13 PM

How do you "enumerate" seeing for a given night?

All I can do Is say well it's pretty clear and the stars aren't "twinkling" and call it a good night...

 



#2 TOMDEY

TOMDEY

    Viking 1

  • -----
  • Posts: 910
  • Joined: 10 Feb 2014
  • Loc: Springwater, NY

Posted 11 July 2018 - 11:31 PM

What you've just described captures nearly all of it. The next step up would be a 60mm grab-n-go for a quick check. Seeing can be quite fickle. There are high-end seeing gizmos that typically train on Polaris and report a running metric.  Tom



#3 Stonius

Stonius

    Sputnik

  • *****
  • Posts: 45
  • Joined: 28 May 2016

Posted 11 July 2018 - 11:46 PM

A lot of the guys who throw numbers around with confidence are photographers. Their software allows them to measure the exact resolution the seeing affords them. I find eyeballing to be fairly inexact myself.

 

Cheers

 

Markus



#4 DLuders

DLuders

    Mercury-Atlas

  • *****
  • Posts: 2710
  • Joined: 10 Apr 2017
  • Loc: Spokane, WA

Posted 12 July 2018 - 01:40 AM

The website ClearDarkSky.com has a graphic for various sites in Indiana to show the "Seeing" realtime conditions, and a forecast.  For example, here is the data for the Logansport, IN site and the "Seeing" scale of 1-5.  Logansport has a 4/5 "Good Seeing" rating right now --    

 

Logansport ClearDarkSky.JPG

 

Seeing.JPG



#5 BQ Octantis

BQ Octantis

    Mariner 2

  • -----
  • Posts: 261
  • Joined: 29 Apr 2017
  • Loc: Outback NT, Australia

Posted 12 July 2018 - 02:10 AM

I'm not so fortunate to have a Clear Sky Chart for central Australia. But Meteoblue has excellent seeing forecasts (fairly accurate out to a couple of days). Here's your forecast (assuming you're somewhere close to Bloomington):

 

https://www.meteoblu...america_4675057

 

The first seeing index is your seeing; the second is more indicative of the jet stream. You're currently at seeing = 5/5, jet stream = 7 m/s, which is ****-near mythical in central Australia! I hope you were out shooting the planets…

 

BQ

 

P.S. Seeing of 1/5 just doesn't do bad seeing any justice—you know the seeing is really bad when the stars at zenith are twinkling and you can see them moving relative to each other with the naked eye!



#6 Asbytec

Asbytec

    Guy in a furry hat

  • *****
  • Posts: 13031
  • Joined: 08 Aug 2007
  • Loc: Pampanga, PI

Posted 12 July 2018 - 02:23 AM

Here's my favorite site for predicting seeing. The link is for the Philippines, but the service is in Australia. Browse the site for your location. White is excellent. Lot of white on the current map.

www.bom.gov.au/australia/charts/viewer/index.shtml?type=windbarb&level=gradient&tz=UTC&area=Ph&model=G&chartSubmit=Refresh+View

#7 dhaval

dhaval

    Vendor

  • *****
  • Vendors
  • Posts: 918
  • Joined: 21 Jul 2008
  • Loc: Round Rock, TX

Posted 12 July 2018 - 10:18 AM

The easiest way to do this would be to take an image and use PixInsight (or any other software) to measure FWHM of the stars. That should give you very good indication of what the seeing is like. You can do this after the fact as well - meaning after you've shot through the night. 




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics