Author: stephanievaonis

Travel journal

Observing the Sun with Vespera and Stellina

Observing the Sun with Vespera and Stellina

When fitted with their optional solar filters, which transmit only 1/100,000 of the solar radiation, Vespera and Stellina can be used to observe some of the phenomena on the Sun’s surface without risk to the instrument or your eyes since the image is transmitted by the instrument’s built-in sensor. The Sun’s activity is currently increasing, which means now is a good time to start this new type of observation and enhance your experience with Vaonis observation stations even in daylight.


vespera and its solar filter

The Vespera solar filter is easily fitted to the front of the observation station’s lens and is automatically recognized by the Singularity app so you can start your solar observation with complete peace of mind.

1. What part of the Sun can you observe?

The Sun comprises several layers. Although it has no solid surface, one of the outer layers – called the photosphere – is the source of more than 99% of solar radiation. In practice, the photosphere is what is referred to as the Sun’s surface, and it is this layer that you can observe with Vespera and Stellina fitted with the solar filter.
The photosphere is about 400 kilometers thick and has a temperature of about 5500°C.

sun structure

The structure of the Sun. Vespera, fitted with the solar filter, allows users to observe the photosphere – Illustration: Sébastien Aubry.

The part around the photosphere is the solar atmosphere. Its lower part is called the chromosphere and is only observable with special instruments able to filter the part of the light spectrum corresponding to H-alpha emission. We can also see fragments of it (solar prominences) during a total solar eclipse (pink spots on the edge of the disk).
Finally, the upper part of the solar atmosphere is called the corona and can be observed either with a specific instrument called a coronagraph, or with the naked eye during a total solar eclipse.

2. What can you see on the Sun’s surface when using Vespera and Stellina fitted with the solar filter?

The photosphere has a relatively uniform appearance without permanent formations, unlike those that can be found on the planets or the moon. However, isolated or groups of dark spots appear regularly. These are known as sunspots, which can be clearly seen with the observation stations. However, sometimes the Sun’s surface does not have any spots (see below for more explanations).

Image of the Sun showing sunspots captured with Vespera fitted with the solar filter.

The lifespan of a sunspot varies from a few days to several weeks. They follow the rotation of the Sun but also have their own movements across the surface. The aspect of the solar disk changes every day.
By carefully observing the biggest spots and groups of spots, you will notice that the very dark center of the spots (the umbra), is often surrounded by a halo that is not quite as dark (the penumbra).

Sunspots are cooler regions with a temperature of about 3500°C. They are the result of loops of particularly intense magnetic fields which “break” the photosphere and limit the renewal of matter coming from the underlying layers of the star.
The smallest spots are a few thousand kilometers across while the largest ones reach 50,000 kilometers in diameter. They are so large they could hold Earth several times over.

On the edge of the solar disk, near isolated or groups of spots, you may be able to observe brighter areas. These are faculae. The contrast between them and the rest of solar disk is not as strong, so they are much more difficult to observe than sunspots. They are only visible along the periphery due to the apparent darkening of the edges of the solar disk. The faculae are hotter magnetic regions (about 8000°C). They can be grouped into a very large range of faculae. On the image below, obtained by computer processing of images captured by Vespera, faculae are visible around the edge of the disk.

Computer processing of images of the Sun captured with Vespera highlighting the photospheric faculae

3. Observing and measuring the Sun’s activity with Vespera and Stellina

The number of sunspots at any given time is extremely variable and depends on the intensity of the solar activity. Over more than a century of observation, astronomers have noticed that the number of spots varies regularly according to a cycle of about 11 years. At the beginning of each cycle, the Sun is nearly devoid of sunspots. The number gradually increases to reach a maximum before decreasing again. The solar activity cycle is intimately linked to the dynamics of the Sun’s magnetic field. Thus with each cycle, the magnetic field reverses.

With Vespera and Stellina, you can regularly count the sunspots and thus monitor changes in the Sun’s activity. We are currently in the early stages of Solar Cycle 25 (counting from when recording such cycles began). The number of spots is still low but will gradually increase. This is a good time to start monitoring the cycle to see how it evolves.

Changes in the number of sunspots. The pattern clearly shows a cycle of about 11 years.

Although we know how long the solar cycle is (even if it can vary by two or three years), it is much more difficult to predict the maximum intensity that each cycle will reach. Monitoring and comparing with previous cycles can provide clues.
The current cycle is expected to peak in the summer of 2025.

Method for measuring and monitoring the Sun’s activity.

If you begin a regular solar activity survey with Vespera or Stellina, it is important to use the same instrument the entire time. If you alternate between telescopes with different features, you will not see the sunspots with the same degree of accuracy, which will influence your count.
There is a fairly simple spot count method that provides a good indication of solar activity. It was developed in 1849 by Swiss astronomer Johann Rudolf Wolf and bears his name: the Wolf number. It is calculated using the following formula:

R = t + 10g

R is the relative sunspot, or Wolf, number, which represents the intensity of solar activity, s is the number of individual spots counted, and g is the number of groups of spots counted. An isolated spot is counted as a group.

This is because depending on the sharpness of the image obtained, it can be difficult to distinguish small spots that are very close to each other. Similarly, the notion of group may seem ambiguous. What is important is to follow the same rules for counting over time. The Wolf number therefore depends on your means and methods of observation.

By making regular observations, you can see how sunspots evolve and which ones are actually part of the same group, since those in a group move together.

For example, in the image below captured by Vespera on July 14, 2022, at least 40 spots and five groups can be counted.
R = 40 + (10 ? 5)
R = 90
The Wolf number is 90.

Counting the number of sunspots and groups of sunspots.

4. Observing and measuring the differential rotation of the Sun with Vespera and Stellina.

Sunspots are driven by the rotation of the Sun. Because they have a lifespan of several days, by capturing a new image of the Sun each day you can see their movement and measure the Sun’s rotation speed. The longest lasting sunspots can even be followed over several rotations.
The Sun does not have a solid surface and its rotation is not uniform. It is faster at the pole than at the equator. This is called a differential rotation. The sunspots closer to the poles thus cross the solar disk more quickly.
An interesting and amusing experiment consists in making an animation video of the Sun’s rotation and the changes in the spots using a set of images taken at regular intervals.
To do this, you will need to know the orientation of the axis of Sun’s rotation in relation to the image captured by Vespera or Stellina to align each image identically. This orientation depends on the date, time and place of your observation.
To determine this information, you might try using the “TiltingSun” software that can be downloaded at the following address:

To locate sunspot positions, measure the Sun’s rotation or make an animation video, you will need to know the orientation of the Sun in the image.

5. How to start observing the Sun with Vespera and Stellina

To observe the Sun, you must use the solar filter (buy it here). Make sure you have the latest version of Singularity. Launch the app, select your observation location, and go to the Space Center to choose the “Solar Mode” function. Then follow the on-screen instructions.

After fitting the solar filter on your observation station, choose “Solar Pointing” from the Space Center tab.

Because solar observation is done during the day, there is no visible star that the observation stations can use to perform astrometry (detection of a star field that Vespera and Stellina can use to calibrate their position in the sky) and initialize, as is possible at night. This is why you should point your observation station as precisely as you can towards the Sun.
This is very easy to do by observing the shadow of the telescope on the ground. Turn your Vespera or Stellina manually on its base. The telescope is correctly aligned when the Sun’s rays pass through the gap between the arm and the body of the telescope and cut the shadow in half. The telescope then takes over and performs a scan to accurately point to the Sun and track it.

Left: Vespera is not properly aligned – Right: Sunlight passes through the gap between the arm and the body of Vespera; the telescope is correctly aligned.

Once the Sun is correctly targeted, Vespera proposes an image of it showing the relative size based on the different planets along with the stars that would be visible around the Sun if we could block out the daylight.
To retrieve an image for the various experiments mentioned above, choose the “raw image” of the Sun.

Choose to observe the Sun as if you were on another planet in the solar system or choose the raw image to perform various experiments on sunspots and the Sun’s rotation.


Never observe the Sun directly through an optical instrument that is not equipped with a specific protective filter. Never point Vespera or Stellina towards the Sun if your observation station is not fitted with a Vaonis filter.

Tips & News, Travel journal

Maintenance tips for your observation station

Stellina and Vespera are robust telescopes designed to be used as often as possible and to be taken with you to your favorite observing sites or even when traveling. They are also optical and mechanical instruments of great precision. Some handling and maintenance precautions are necessary to maintain performance over time.


1. The advantages of the Stellina and Vespera design

Vaonis observation stations are closed-tube instruments unlike conventional main mirror telescopes with open tubes. This makes them less fragile and easier to maintain. There is less risk of dust getting into the tube, the optical system is better protected and the mirror does not need to be aligned regularly to maintain performance, even after being moved.

2. Tips for transporting your observation station

Two accessories are available for transporting your Stellina:

  • The backpack allows you to protect the observation station when transporting it over short distances or when walking to an observation site not accessible by vehicle.
    > See the backpack
  • The carrying case further protects Stellina for transport in a vehicle and even on planes as hold luggage. If you do transport your instrument as hold luggage, inform the staff at check-in and ask them to put a “FRAGILE” sticker on the case.
    > See the transport box


Backpack and fly case for Stellina

Backpack and transport box of your Stellina observation station.


  • Thanks to its compact design, Vespera can be adapted to many models of travel or sports bags.
  • In all cases, during transport, be sure to keep the telescope in its protective case to limit micro-scratches on the shell.

3. Tips for using your observation station

  • Stellina and Vespera have been designed to operate optimally at between 0° and 40° Celcius.
  • Stellina has a humidity sensor. If it rains, the optical arm closes automatically. However, the observation station is not designed to withstand heavy rain. Therefore, if the weather is uncertain, do not leave your telescope outside unattended if it is not sheltered.
  • When it is windy, do not install StellinaVespera near sandy or dusty areas to avoid sand grains being blown onto the optics and the shell, or dust being deposited on the lens.
  • Avoid exposing the instrument to the sun for too long to prevent the shell from yellowing.
  • Before folding the Gitzo tripod at the end of your observation, dust the retractable parts of the legs to prevent sand grains from entering the legs, scratching them or jamming the mechanism.

4. Tips for cleaning your observation station

Optical system.

Ideally, the front lens should be cleaned as little as possible. It is sometimes preferable to leave some dust or very light traces rather than risk a hazardous manipulation which could damage it. Avoid contact with fingers to avoid leaving greasy marks and with abrasive objects to avoid scratching. It is possible that some dust may be present inside the optical tube. This does not affect the performance of the observation station.
If, despite your precautions, dust or greasy marks become a nuisance, here’s how to proceed:

  • Make sure there is no moisture on the lens.
  • Start by removing the dust with a feather brush or a blower (available at photo supply stores).
    Never wipe the lens while there are dust particles on its surface. You could scratch it.
  • If dust remains stuck on the lens, you can try to put a few drops of non-calcareous water on it (prefer distilled water to avoid additional deposits).
  • Once the lens is free of dust, you can use an optical wipe to remove greasy deposits and other marks. Proceed gently without putting too much pressure on the lens.
  • Start by removing the dust with a feather brush or a blower (available at photo supply stores).

Shell and tripod.

  • The shell of your observation station can be cleaned with a microfiber cloth and an acetone-free household cleaner (window cleaner, multi-surface cleaner, white vinegar).
  • Check the mounting base to make sure nothing will interfere with its proper placement on the tripod.
  • You can grease the legs of the Gitzo tripod to make them slide perfectly by using the Gitzo tripod grease provided.
    > Order tripod grease

5. Tips for storing your observation station

  • If moisture is present on the telescope, let it dry in a ventilated area before storing. If you notice moisture on the lens, you can leave the device with its anti-fog system on for half an hour to an hour after your observation.
  • If you have to transport it in a crate or bag from your observation site to your home, take it out of the transport crate for a few moments when you get home.
  • Following observation in very low temperatures, avoid storing the observation station immediately in a heated area to limit thermal shock and moisture condensation. Leave it for a few moments in a sheltered, unheated and ventilated place.
  • When storing the instrument, close the optical arm and the battery compartment and use the cover to limit dust deposits on the lens, the connectors and the interior of the telescope.

6. About the battery pack

  • Even if you aren’t going to use the battery for a long period of time (several months) it is still advisable to recharge it from time to time to avoid premature aging and discharge.
  • The battery contains lithium. It should be stored in a dry place at room temperature.
  • Do not use damaged USB cables.
  • If you plan to transport your observation station by plane, keep in mind that batteries are not allowed in the hold and must be taken with you as carry-on luggage.

What to do if you have a problem with your observation station

If your telescope is no longer working properly, if it has been damaged or has defects, you can contact our customer service department by phone at +1 855-399-0947 or with WhatsApp at +33 6 70 34 09 03 from Monday to Friday from 10 am to 6 pm (French time). We will do our best to provide you with a solution so that you can use your observation station normally again.

Reminder about the warranty

Stellina and Vespera are precision assembled and should not be disassembled or modified. Any opening of the shell or modification of the mechanical and optical system will void the warranty. To find out the full warranty terms for your product, click here.

Nébuleuse de la méduse
Observations, Travel journal

Lets meet IC 443 Jellyfish Nebula

1h12 AM

Today we embarked on a journey twenty thousand leagues under the sea aboard the Stellina station. We never imagined meeting a huge celestial jellyfish on our way. Bewitched by the movements of her radiant and transparent body, we spent 5 hours watching her swimming majestically in this sea of stars called Gemini.

What marine animal are we going to meet again?

IC 443 Jellyfish Nebula

Object: IC 443 Jellyfish Nebula
Date: 08/02/2021
Total exposure time: 5 hours
Location: United-States
Auhor: Brian P.

Check more of our observations on our blog.

Tips & News

Vespera, Vaonis newborn star


  1. Vespera
  2. What are the differences with Stellina ?
  3. Photos
  4. Frequently asked questions
  5. Press & media Kit

1. Vespera

Two years after the launch of Stellina, Vaonis is pleased to present its new creation, Vespera. Our team has put all of Stellina’s technology into a smaller, lighter but also more affordable version to make astronomy even more accessible.

We have highlighted the essential and the best of Stellina to design Vespera, which still offers the same simplicity of use, thanks to its initialization, automatic pointing and tracking system, its intelligent and very powerful image processing.

Vespera is designed for everyone, for sky lovers looking for simplicity and unforgettable experiences to share. As for Stellina, the instrument offers more manual possibilities (image processing), as well as a larger aperture and resolution.

Go to the Kickstarter page  to join the community on a new odyssey!

2. What are the differences with Stellina ?




5 kg (11 lbs)

11,2 kg (24,7 lbs)


40 cm (15 in)

49 cm (19 in)


20 cm (8 in)

39 cm (15 in)


9 cm (3.5 in)

13 cm (4.7 in)


Apochromatic Quadruplet

Apochromatic Doublet

Lens special features

Extra low dispersion
S-FPL52 equivalent (ULD)
with lanthanum glass

Very low dispersion
S-FPL51 equivalent (ED)
with lanthanum glass


50 mm

80 mm

Focal length

200 mm

400 mm

Focal ratio



Field of view

1.6° x 0.9°

1° x 0.7°




Field derotator


Image sensor

Sony IMX462

Sony IMX178


1920 x 1080 (2MP)

3072 x 2080 (6,4MP)

Sensor size



File formats



USB port (pictures download)

(with Wi-Fi)


Auto focus



Light pollution filter



Dew control



Temperature/humidity sensor


Battery type


External (powerbank)

Battery life



Water Resistance



Multi user mode

Up to 5 users

Up to 10 users

 2021/2022 Developments

Solar pointing

Connected battery

Connection to Wi-Fi hotspots

Scheduling of observations

Up to 3 objets


Expert Mode (camera control)

HDR Image processing

Pictures stocking in the app

Up to 100 images

Up to 100 images

Mosaic Mode

5x sensor field

16x sensor field

Resolution difference (proportionally)

M27 Dumbbell nebula Vespera

Photo captured by Vespera (original size: 1920×1080)


M27 Dumbbell nebula Stellina

Photo captured by Stellina (original size: 2900×1972)

Size difference

3. Photos

Vespera’s development is ongoing. Photos were taken with the first prototypes in a peri-urban environment, Bortle 6. Click to enlarge the pictures.

Exposure time :
M31 Andromeda Galaxy: 177x10s (30min) – M13 Hercules Cluster: 177x10s (30min) – NGC6992 Veil Nebula: 330x10s (55min)
Moon: live – M27 Dumbbell Nebula: 177x10s (30min) – M42 Orion Nebula: 200x10s (33min)

4. Frequently asked questions

Is Stellina more powerful than Vespera? Does it offer a better photo quality?
You can find all the answers to your questions (pre-orders, deliveries, techniques) on this page :

5. Press & media Kit

We put at the disposal of journalists, influencers, partners and associations :

  • a general presentation (10 slides)
  • a press release
  • photos
  • videos
  • photos taken by Vespera

Access the folder by clicking here.

m8 process
Travel journal

Friday, July 31

12:56 AM

This month, we’re heading to the constellation of Sagittarius from our base in Namibia. Fleeing the overwhelming heat of the world’s oldest desert, the Namib, we’re diving into the heart of the pink Lagoon. The nebula stretches deep over 100 light years. On our way, we cross star reefs and Bok globules. We narrowly avoid being engulfed by a tornado caused by the emission of ultraviolet rays from a massive star, tunneling into an even darker region. Halfway in, we find ourselves in the area called the Hourglass Zone and witness, with awe, the birth of young stars that will in turn illuminate this immense expanse of cosmic gas..

m8 process

Object: M8 Lagoon Nebula
Date: 01/07/2020
Stacked images: 360x10s
Total exposure time: 1 hour
Location: Namibia
Author: Sebastien A.

NGC5128 (233 exp)
Travel journal

Monday, June 1

02:12 AM
Fifth-brightest galaxy in the sky, Centaurus A mesmerized us all.

Glaciers melting in the dead of night.
And the superstars sucked into the supermassive blackhole*
You set our Stellina alight.

NGC5128 (233 exp)

Object: Centaurus A Galaxy
Date: 01/06/2020
Stacked images: 174x10s
Total exposure time: 30 minutes
Location: Namibia
Author: Sebastien Aubry

*Extract from Supermassive Black Hole (Muse)


Travel journal

Tuesday, May 5

01:34 AM
Off we go, on the wings of adventure, riding the Atlas comet through outer space. Into the roaring unknown, we’re uncovering space’s mysteries, remembrance of things past. As we retreat, temperatures warm and our comet is fading away. Farewell Atlas!
Let take the Swan’s way.


Object: Comet SWAN C/2020 F8
Date: 05/05/2020
Stacked images: 103x10s
Total exposure time: 1 hour and 46 minutes
Location: Keetmanshoop, Namibie
Author: Sebastien Aubry and Pierik Falco


Object: Comet ATLAS
Date: 23/04/2020
Stacked images: 535x10s
Total exposure time: 1 hour and 37 minutes
Location: Switzerland
Author: Pierik Falco

Travel journal

Friday, April 3

At first, we thought that someone had thrown a snowball on our lens. But is was not melting. The smear became crispier, ready to bang in the universe.

Object: NGC 5139 Omega Centauri
Date: 03/04/20
Stacked images: 147x10s
Total exposure time: 24min
Location: Namibia
Author: The Adventurer of the Third Planet for Vaonis

Travel journal

Thursday, March 19

We were cruising through the Carina, heading to HD95358 star’s station for a research project, when we got lost on our way, deviated by unexpected interstellar winds. It was darkness into darkness, a space where time seemed like it has never begun. We managed to find our way back, annoting our discovery in our journal, determined to unveil the secrets of this dark nebula some day.

Object: Dark nebula near HD95358
Stacked images:
Total exposure time:
2 hours and 7 minutes