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Herschel's telescopes and other things to see at the Royal Observatory in Madrid

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#1 RazvanUnderStars

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Posted 13 June 2022 - 09:33 AM

I revisited Madrid (by itself a fabulous city) this spring and went to tour its superb Royal Observatory; the other day's nice post about the observatory in Lisbon made me realize I forgot to post about the Madrid one. 

 

The building was designed by one of the most famous architects of the time, Juan de Villanueva, who also designed the stunning Prado Museum which is minutes away by foot. BTW, if you haven't visited Madrid, it's a very walkable city, with things to keep you busy for weeks and still within an hour's walk. Here's the Google Maps location for the observatory to anchor it.

 

The observatory hosts a number of original instruments used for observing the skies as well as theodolites, magnetometers, sextants, chronometers, pendulums and more, with many from the 19th century, but some are older such as a heliometer by J. Dollond from 1785.

 

The highlight of Madrid's observatory is a reconstruction of Herschel's 25-foot telescope seen in the attachment (I left other tourists for scale), which is also seen in detail in this video produced by the observatory (in Spanish, you can use the auto-translate function).

 

The original telescope was destroyed by Napoleon's army but Herschel's original 60-cm mirror (~1796, a spare copy exists in London) is for display as well, as well as two of its original Newtonians (~1796, one with 19cm diameter, another with 16cm), seen in the second attachment. In the same hall there's a Foucalt's pendulum and a number of instruments for display.

 

Note: You must book a guided tour in advance through the official site and sell out quickly as they are a few only per week. At this time the tours are in Spanish only (I happen to have learned it so it was a nice little reward but you'll understand a lot based on the existing interest in this field).

 

(to be continued).

 

Razvan

 

_25ft.jpg

 

_hall.jpg


Edited by RazvanUnderStars, 13 June 2022 - 09:34 AM.

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#2 RazvanUnderStars

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Posted 13 June 2022 - 09:56 AM

Among the exhibits, there's a transit telescope (Repsold, 1853), 15cm diameter, FL 209cm, seen from below in the first attachment below. How is that for an observing chair? :-), a comet finder by Utzschneider & Fraunhofer (1850) and a heliometer by Dollond (1785), in the second picture.

 

For details about the exhibits, I'd recommend buying the official catalog from the observatory's small shop. It's in Spanish only, but very understandable anyway by someone with astronomy knowledge.

 

You can also see a number of detailed videos at https://www.ign.es/w...torio-de-madrid. Since they are on YT, you can use the auto-translate function.

 

Hope you'll enjoy them as much as I did!

 

 

_transit.jpg

 

_heliometer.jpg

 

_catalog.jpg

 

_catalog2.jpg

 

 

 


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#3 PirateMike

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Posted 13 June 2022 - 10:54 AM

Very Nice! waytogo.gif

 

I may be totally wrong on this, but from what I understand about the use of Herschel's big telescope is that he didn't use eyepieces as the scope doesn't have a secondary mirror. I assume that it is true that he sat at the open end of the telescope and used a small handheld refractor (I guess you could call it an eyepiece) and viewed sections of the main mirror directly through it.

 

Can you tell me if this is correct or not?

 

 

Miguel   8-)

 

 

.


Edited by PirateMike, 13 June 2022 - 10:55 AM.


#4 RazvanUnderStars

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Posted 13 June 2022 - 01:04 PM

I think that's the case, indeed. I don't have a closeup of the observing platform myself (it wasn't possible for visitors to go up the ladder) but found one in the catalogue so I cropped the area which shows the small refractor.

 

Also, regarding the telescope's bigger (40-ft) brother, Wikipedia reads "Herschel eliminated the small diagonal mirror of a standard newtonian reflector from his design and instead tilted his primary mirror so he could view the formed image when he stood in an observing cage directly in front of the telescope. This saved on the severe light loss the image would suffer if he had used a speculum metal diagonal mirror. This design has come to be called a Herschelian telescope" (BTW, the original mirror can be seen in the video linked in the first message starting at 1m24s).

 

o.jpg

 

 

 

I may be totally wrong on this, but from what I understand about the use of Herschel's big telescope is that he didn't use eyepieces as the scope doesn't have a secondary mirror. I assume that it is true that he sat at the open end of the telescope and used a small handheld refractor (I guess you could call it an eyepiece) and viewed sections of the main mirror directly through it.

 

Can you tell me if this is correct or not?.

 


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#5 PirateMike

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Posted 13 June 2022 - 02:08 PM

Oh man, that is so cool. I wonder what the heavens looked like through the little scope.

 

 

Thanks,

Miguel   8-)

 

 

.


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#6 Astrojensen

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Posted 13 June 2022 - 03:31 PM

Very Nice! waytogo.gif

 

I may be totally wrong on this, but from what I understand about the use of Herschel's big telescope is that he didn't use eyepieces as the scope doesn't have a secondary mirror. I assume that it is true that he sat at the open end of the telescope and used a small handheld refractor (I guess you could call it an eyepiece) and viewed sections of the main mirror directly through it.

 

Can you tell me if this is correct or not?

 

 

Miguel   8-)

 

 

.

This is incorrect. Many of Herschel's original, homemade eyepieces have survived. The scopes with a front-end view also used normal eyepieces.  

 

The method you described can't work at all in practice. 

 

 

Clear skies!

Thomas, Denmark 


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#7 dUbeni

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Posted 14 June 2022 - 09:06 AM

Thank you for this report RazvanUnderStars, I will visit it next time I'm in Madrid.

Apparently the Madrid observatory is much better organized, I liked the link's you provided.

 

CS

Bernardo 



#8 RalphMeisterTigerMan

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Posted 17 June 2022 - 03:31 PM

I find it interesting that good-old William always seems to have referred to his vaious telescopes by their length and not the diameter of the primary mirror. I always found that quite confusing.

 

Clear skies and keep looking up!

RalphMeisterTigerMan


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#9 jgraham

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Posted 17 June 2022 - 03:48 PM

That was very common for the time. If I recall right Charles Messier is often described as using a 3 foot telescope. I also seem to recall the Herschel built two 20 foot telescopes; one with a 12" mirror the other with an 18" mirror.

 

Neat stuff.


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