Where is it? Celestial coordinates explained

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What's the difference between RA/DEC and Alt/Az? Why use both? In this video I will explain what a coordinate system is, and why we often use both an equatorial coordinate system (RA/DEC) and a horizontal coordinate system (Alt/Az) in amateur astronomy. This is part of a series called Five Minute Fridays where I will be explaining one concept in under five minutes each week. #fiveminutefridays #nebulaphotos
Book recommendation-- Longitude by Dava Sobel: amzn.to/3itld5o
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Creative Commons Media:
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Celestial Sphere by ChristianReady, CC BY-SA 4.0, via Wikimedia Commons
Ra and Dec on celestial sphere by Tfr000 CC BY-SA 3.0 via Wikimedia Commons
Ra and dec demo by Tfr000, CC BY-SA 3.0, via Wikimedia Commons

Опубликовано:

10 июн 2021

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Комментарии : 95

@justindame 3 года назад

I look forward to these five minute Fridays so much! Every night at dinner with my kids we discuss "What we've learned" and I always am excited to bring these up to share with them. Thanks Nico!

@flyfisher8475 3 года назад

Beautully explained Nico. You certainly have a gift for making things clear.

@AnkitGupta12 3 года назад

Hey nico!! I have been following you for months now. Love your new series where you speak about the technical know how's to help amateurs like us. Keep up the good work!👍

@tachyon3.14 3 года назад

Week 4 of appreciating Five Minute Fridays

@mikey2d650 6 месяцев назад

Finally able to understand! Thank you so much !

@alex.petkevich 3 года назад

Waiting for next friday! This is gonna be very interesting!))

@FreeRealEstatepage 3 года назад

You’re like what I would consider my favorite college professor! The way you deliver your info is so clear and detailed, making it enjoyable to learn. I would love a video about ace seconds and how they affect photography.

@alanalain4884 2 года назад

The most explanative video for a beginner to understand the ecliptic, Zodiac, contellations positions and coordinates in few minutes (well, alt/az was easy too). Many thanks.

@avt_astro206 3 года назад

Fantastic Video Nico!! This Was Really Informative, enjoyed it!!👍

@Paulus449 3 года назад

Great video and full of useful information as always. Thanks Nico!

@grigoryvidishev1810 3 года назад

Thank you Nico, keep going!

@Gthefray 3 года назад

amazing video! this is so interesting & well explained. gotta go watch some more videos now! can’t wait to see the next one

@philkidd 3 года назад

As usual, great information Nico! As complicated as it is, you always make things sound so easy!

@hbmike47 3 года назад

Opting to address this subject with a five minute Friday video may not be the wisest choice. This is one of those "i need to go back to the long video format" to explain this so you really get it subjects. Not to say rambling (Ha Ha). More like use the focus on exactly what you want to say like you did for the 5 min version and extend it into a long video (maybe in a couple of parts.. there's only so much people can absorb at once). You got through it, but IMO you are really good at teaching and explaining things, and with some great visuals from some of the software packages available these days it something I really think you could do a couple of videos that could become one of those 'stands the test of time' references. Celestial coordinates is something that is not easy for people to wrap their heads around. Thanks for putting yourself out there !

@NebulaPhotos 3 года назад

I agree. It felt like something I could explain in 5 minutes, but as soon as I started actually trying to condense it in to 5 minutes, I kept thinking 'what have I done?' lol

@stanmonish3532 6 месяцев назад

Thank you for describing in clear detail how the declination-right ascention coordinate system works. Your description and graphics makes it very easy to understand.

@markorcutt2115 3 года назад

I am struggling with locating a target and then keeping it at the center of my field of view. I am limited with the equipment I have acquired to date in the past several months. Thank you for starting with these basics. I use a Omegon Mini Track LNX2 to mechanically track somewhat successfully, especially when the house is not blocking Polaris. I even used PhotoPills AR to simulate Polaris’ position and sighted an alignment, then tweaked the position to keep a star on track.

@DavesAstrophotography 3 года назад

Thanks Nico, love these explanation videos :-) One to add to your list is resolution limits Rayleigh and Dawes. Often see them quoted on telescope specification.

@ManishFrenchStudio 3 года назад

Superb video dear, thank you for sharing 🙏😀🎉🎉🎉🎉

@victormultanen1981 3 года назад

such a nice from you to explain all that stuff!

@Metaldetectiontubeworldwide 3 года назад

Always a Joy seeying a notification of you and your channel ☆♡♧

@W_Parker_Astro 3 года назад

Excellent explanation, you have a way of explaining things so that I easily understand them, a massive thank you 🙏🏼 from me 😃

@aay_its_sage 3 года назад

I love these 5 minute Fridays

@tomaszsosnowski9279 Год назад

Regarding 2:22 I did see a chart of a UT times of march equinox. It's a different time each year, less then six hours apart per year. That makes the application by novice stargazers even trickier.

@TheBardo24 3 года назад

FMF's are so good! Love it!!

@steveg4iwr 3 года назад

A great video that actually made sense. I only had to watch it twice.

@AmatureAstronomer 9 месяцев назад

Informative!

@shingoburg 3 года назад

great explanation, thank you!

@Pipe-organ-recordings 3 года назад

Great job explaining it.

@peteallennh 2 года назад

Ditto the other comments below. Your simple, clear explanations are great. You have put together an excellent channel.

@BhojinderpalSingh 3 года назад

Very helpful!

@Spaced_Out_Bill 2 года назад

Fantastic video, Thank you! If you ever run out of ideas for a Five Minute Friday video, RU-vid could really use your expertise explaining what Debayering is, how it works and when to use it or not. I can hardly find anything on the subject. 🔭

@GalaxyArtMedia 3 года назад

Nice video!

@jeddymo7052 3 года назад

Thanks Nico! Very good as always. Wondering if you can add to this a discussion of the different types of meridians. I know the Alt/Az meridian on my software indicates when I need to do a meridian flip of my equatorial telescope when the target moves through that. I don't know why. But the software has several other meridians. Celestial. Eclyptic. Galactic. Brain exploding now.

@astromatz 3 года назад

Wow, five minutes is really very short... well done! 👍

@ashiqueashhad8665 3 года назад

I like the way you explain 😄

@thomascloutier9767 11 месяцев назад

Longitude is an excellent book.

@mahitoshray6691 2 года назад

I would like to learn how to convert equatorial coordinates to horizontal. Its little difficult to understand so it will be nice if you could make a short video on that

@pukhrajmansion8445 19 дней назад

Good 👍

@erikmardiste 3 года назад

Thank you thank you thank you.

@giuseppeamoruso7220 11 месяцев назад

Hi, Out of curiosity, do the stars appear to move faster the closer you are to the equator? So that while taking a photo you need to use lower shutter speed? I've read that the closer you are to the equator the faster the sun set so I assume that it is the same for the othe celestial object!!? Thanks Thanks

@chrisross2916 3 года назад

Very informative explanation, but at 42N 71E - you're in Kyrgystan? :-)

@mikegordonbrasov161 Год назад

¿ANY IDEA HOW CAN I LOCATE THE FIRST ARIES POINT FROM ANY PLACE? ¿SOME KIND OF DIY CLINOMETER GADGET THAT HELP ME LOCATE THE VERNAL POINT, AND AFTER THAT FINDING A STAR BY IT´S DECLINATION AND AR? JUST FOR THE PURPOSE OF PRACTICING

@karlharvymarx2650 Год назад

Kind of wish you hadn't skipped some of the RA explanation with "there's an app for that" since I'm the poor schmuck making one of those apps. I guess that's out of scope for the channel (pun unfortunately intended).

@matthewb8229 3 года назад

Declination always made sense to me, but RA...my brain can't wrap around it. I've had it explained to me, and it seems to make sense, but then I get out to apply what I've been taught, and it just confuses me. I still try to understand it, however. One of these days... Edit: I had to come back. Goofing around in Stellarium, I figured out what was confusing me! I was using the eclitptic as the...horizon, not the terrestrial horizon!

@NebulaPhotos 3 года назад

Glad it's making more sense Matthew. It took me a long time as well! I do get it now, but I fear it's one of those concepts that takes most people a while to fully 'get' and requires a bit of exploration on one's own as you did in Stellarium.

@NatarajanGanesan 3 года назад

Ujjain was the equivalent of GMT back in the times

@Yanthungbemo 3 года назад

Is there an app that can tell me the alt-az coordinates of an object on a phone? I don't think it's possible in Stellarium for mobile. Also, thanks for all these tidbits of knowledge you keep giving us. Really helpful as I'm too lazy to go reading it up.

@NebulaPhotos 3 года назад

On Android, SkEye shows both the Equatorial and Alt-Az coordinates, and it's free. For paid apps, Sky Safari (android or iOS) is available at different levels, the cheapest one though, the $2.99 version, includes alt-az coordinates.

@Yanthungbemo 3 года назад

@@NebulaPhotos thank you!

@ashzole Год назад

so what was the prime meridian in bibical times on a celestial sphere????

@3f34f2f4 3 года назад

I never knew you were from Kyrgyzstan ;)

@NebulaPhotos 3 года назад

😂

@kshitijvi7126 10 месяцев назад

4:24 which software is that ?

@thequeenofswords7230 Год назад

...but I like crunching fancy equations by hand? Thanks for the upload, still. ^_^

@tomaszsosnowski9279 Год назад

Right ascension is tricky. I did check the one for the moon. It did read 18 hours. But on the 20th of march 2023 the sun and moon were rising one hour apart, the sun was first over the horizon. And Venus right ascension is even more perplexed, it's about 2h, but it doesn't tell anything if Venus is west or east of the sun in the solar system...

@betaorionis2164 5 месяцев назад

Only stars have a fixed right ascension, because they don't move relatively to the Earth (well, they appear to very slightly move due to parallax and proper movement, but we can disregard it for practical purposes). But the Solar System objects like the Sun, the Moon or Venus are moving relatively to the Earth and relatively among them, so their position in Astronomical Coordinates (which are based on the Earth's position) is continuously changing. Their right ascension is only valid at a given moment, but not the following day or even some hours later.

@eladhershko9224 2 года назад

Can someone help me understand the right assntion ,if, on the vernal equinox,on 00:00 i look to my zenith,i see 0 degrees,hence,the celestial clock is now 0? And if i look east at 45 degrees it will be 03:00 on the celestial clock? If it is really so,my reference point,my zenith on the vernal equinox at 00:00 am,is constantly moving,how is this possible to know the right assntion? Sorry for my poor english.

@NebulaPhotos 2 года назад

Hi Elad, The first sentence you wrote is true if you were standing on Earth's equator at the moment of the vernal equinox. For the second question, let me go back to the example I used in the video, and try explaining with fresh words. Longitude has a fixed reference point geographically. Right Ascension needs both a fixed reference point geographically (the equator) and in time (vernal equinox) since the earth is both constantly spinning, orbiting the sun, and our view of the night sky changes based on where we are standing on Earth. It makes calculating Right Ascension a more drawn out procedure involving lots of math, and you would need to use both date/time and location on earth as inputs to turn equatorial coordinates in to useful horizontal (local) coordinates.

@dobrzansky 3 года назад

How do you find Kirgistan?

@rameshwarprasadchaturvedi8257 3 года назад

Hello sir I am taking a I optron goto eq pro + with orion 80mm st A doublet 400mm focal length weight 2.2 kg so shall I take it I live in bortle 7 so I will use optlong cls filter with a dslr

@NebulaPhotos 3 года назад

Yes, I think that setup will work pretty well. With the 400mm f.l. you may be limited to short-ish exposures on the SmartEQ, but from Bortle 7 that should be fine. I have often done 30s. exposures at 360mm f.l. on the SmartEQ without issue.

@TheStarDreamer Год назад

The thing that annoy me the most is why we still use "Equatorial system", why not use the Solar plane i.e. "Elliptical System" for Right ascension and declination...

@Mandragara 3 года назад

Declination is v. important for untracked imaging

@JemCruz 3 года назад

I keep wondering why you're showing a photo of a vampire and a girl... Then I realised it's a poster on the wall :S

@NebulaPhotos 3 года назад

Lol

@pabloyanez2235 2 года назад

Nico... help out a geologist looking at the starts. In geology we used to use a device called a Brunton to measure the strike and dip of rock units, now a days all the cool kids use an ipad or their cells phones to measure the same thing. The other night while attempting to shoot some deep space objects, it occurred to me that there must surely be a similar app to measure the alt-az of where my lens is pointing (roughly) by laying my phone or iPad across the front of my lens (screen out, back side working like a lens cap). Does such a poor man's finder app exist?

@NebulaPhotos 2 года назад

Most of the planetarium apps can use the iPad or phones compass and gyroscope to work as a rough finder. Try Night Sky app on iOS

@pabloyanez2235 2 года назад

@@NebulaPhotos But they don't work in reverse mode do they? Specifically if I have the back of my device tp the glass on the from of the camera lens and I can see the screen it will show me the sky below the horizon, rather than what the lens is pointed at, no?

@NebulaPhotos 2 года назад

@@pabloyanez2235 Have you seen this video I made?: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-8MF8DByj_Po.html That's how I'd use an app with the phone in the right orientation to work. That said, I haven't found they work perfectly so you will see in the video I use a few different methods in combination to find stuff.

@visheshdubey6818 2 года назад

sir KINDLY UPLOAD MOREVIDEOS

@captgbakos1291 3 года назад

Nico, I hope you meant to say you're 71 degrees west of Greenwich (in Mass), not east. (Otherwise I have been interpreting it wrong all along!)

@NebulaPhotos 3 года назад

Haha, yep, working too fast on this one to get it out on time.

@danielwalker5682 4 месяца назад

Where I live, the Sun is nowhere to be see, in the night sky: not at the Vernal equinox, or any other time!

@mikez104 3 года назад

Very well explained. But I'm still confused lol

@NebulaPhotos 3 года назад

Yep, it's difficult, but keep exploring the topic and you'll get there. Took me a few years to rally get it

@mccarthymccarthy1 3 года назад

Did you mean 71 degrees West?

@NebulaPhotos 3 года назад

Hahahaha, yes

@pinkumia1831 3 года назад

I'm seeing from India

@horizonbrave1533 3 года назад

You legit lost me about 1 minute in. But! I appreciate the attempted breakdown!

@NebulaPhotos 3 года назад

TBH it took me a couple years in the hobby before I could really visualize in my head how Ra and Dec work. It's definitely not intuitive and is maybe a stretch to try to explain in five minutes as I attempted.