Northern Sky Narrowband Survey

A survey of the northern sky, focusing on emission lines of HII (656.3 nm), OIII (500.7 nm), and SII (671.7 nm and 673.0 nm), but also collecting continuum data, started at the end of 2018. The entire northern hemisphere down to DEC=-16° is recorded.

Early results from selected regions can be found in the wide field nebulae section. Any of these images show faint nebulae that haven't been cataloged before (which does not mean that they are unknown). A preliminary list of these objects can be found in a GitHub repository.

A first data release with a complete set of Hα and low-resolution continuum images (instruments 1-4, see below) is scheduled for the end of 2024.

Below are two tables. The first one describes the different instruments, and the second one lists how many of the instruments from the first table are active in which period.

Instrument index	Emission line, Bandwidth / Passband / Filter	Field of view	Aperture	Resolution	Comment
1	656.3 nm (Hα), 3.5nm	7.6° × 5.8°	5 cm	9" (FWHM)	Panasonic MN34230 sensor, f=135 mm lens
2	Bayer CFA + Light pollution filter	15.5° × 10.3°	7 cm	17" (FWHM)	DSLR camera, f=135 mm lens
3	656.3 nm (Hα), 3.5 nm	7.6° × 5.8°	6 cm	9" (FWHM)	Panasonic MN34230 sensor, f=135 mm lens
4	656.3 nm (Hα), 35 nm	7.6° × 5.8°	5 cm	9" (FWHM)	Panasonic MN34230 sensor, f=135 mm lens. Used for exact continuum measurement (wide passband centered to emission line).
5a	410 nm to 550 nm (SDSS G')	6.8° × 4.5°	10 cm	7" (FWHM)	Sony IMX455 sensor, f=300 mm lens
5b	555 nm to 650 nm (SDSS R' + 400 nm to 650nm IR-cut)	6.8° × 4.5°	10 cm	7" (FWHM)	Sony IMX455 sensor, f=300 mm lens
5c	695 nm to 845 nm (SDSS I')	6.8° × 4.5°	10 cm	7" (FWHM)	Sony IMX455 sensor, f=300 mm lens
6a	505.7 nm ([OIII]), 4 nm	10° × 6.8°	6 cm	10" (FWHM)	Sony IMX571 sensor, f=135 mm lens
6b	671.7 nm and 673.0 nm ([SII]), 4 nm	10° × 6.8°	6 cm	10" (FWHM)	Sony IMX571 sensor, f=135 mm lens

Instrument index:	1	2	3	4	5a	5b	5c	6a	6b
Nov 2018 to Apr 2020	4	2
Apr 2020 to Jul 2020	1	2	3
Jul 2020 to Jan 2022		2	3	1
Jan 2022 to Sep 2022		2	3	1	1	1	1
Sep 2022 to Dec 2023			3	1	1	1	1
Dec 2022 to Apr 2023			3	1	1	1	1	1	1
Apr 2023 to Jan 2024			3	1	1	1	1	2	3
Since Jan 2024			3	1	1	1	1	3	3

Images of the instruments

Below are a few photos of the instruments. Click on the images for higher resolution versions.

Both arrays of the Northern Sky Narrowband Survey — All instruments are distributed across two arrays which are shown above.

Array of the Northern Sky Narrowband Survey containing H-alpha and continuum instruments — HII instruments (3 and 4; the four smaller lenses) and the continuum cameras (5a to 5c; the three large lenses).

Array of the Northern Sky Narrowband Survey containing [OIII] and [SII] instruments — OIII and SII instruments (3 × 6a and 3 × 6b).

Selected results

Below are selected result. Click on the images for detailed descriptions and other views.

Orion region in H-alpha and continuum — HII regions and reflection nebulae in Orion constellation. In this false color composite Hα is mapped to red, blue continuum is mapped to green, and red continuum is mapped to blue. Reflection nebulae appear green to blue, while HII regions are red. This region of the sky is full of famous nebulae, such as the Orion Nebula (M42), Flame Nebula, Horsehead Nebula, Barnard's Loop, and the Witch Head Nebula.

Taurus and Perseus region in H-alpha and continuum — Molecular clouds In constellations Taurus and Perseus in front of HII regions. In this false color composite Hα is mapped to red, blue continuum is mapped to green, and red continuum is mapped to blue. Reflection nebulae appear green to blue, while HII regions are red. The bright reddish structure near the center of the image if the California nebula. The greenish nebula at the bottom are the Pleiades.

RGB image of the Milky Way in constellations Vulpecula to Aquila — True color image of the Milky Way form the constellation Vulpecula to Aquila, dominated by massive dark nebulae in front of star clouds.

OIII arc in Gemini — An arc-shaped emission nebula in the constellation Gemini with dominant OIII lines. In this false color composite [OIII] is mapped to red, Hα is mapped to green and [SII] is mapped to blue. The object has already been recorded in far UV surveys. What is new, however, is that this object can be seen in visible light and that it is an OIII emitter.
Interestingly, the arc has been detected in the preview images of the first clear night after the camera array reached its full configuration. Furthermore, it is the first image that contains data from all three emission lines. So, this detection can be seen as the first light of the full array configuration.