# SNR G034.6-00.5

**SNR G034.6-00.5**, also known as **W44**, 3C 392, and CTB 60, is a supernova remnant listed in the Cambridge catalog as G34.7−0.4, which notes the object has been called G34.6−0.5.<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup> It lies in a dense molecular environment and has a mixed morphology, with a radio shell surrounding centrally concentrated thermal X-rays and a pulsar with an associated pulsar wind nebula within its boundary.<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup> The remnant has a flux density of 240 Jy at 1 GHz and a spectral index of 0.37, making it one of the brighter radio remnants in the [Galactic plane](https://www.edgepedia.org/galactic-plane).<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup> Distance estimates span roughly 2 to 3 kpc, with H I absorption suggesting 3.0 kpc, optical absorption 2.1 or 2.7 kpc, and H<sub>2</sub> emission 2.8 kpc.<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup>

| Key fact | Detail |
|---|---|
| Designations | W44; SNR G034.6-00.5; 3C 392; CTB 60; the Cambridge catalog lists it as G34.7−0.4 and notes it has been called G34.6−0.5<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup> |
| Position | Right ascension 18h 56m 00s, declination +01° 22′<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup> |
| Angular size | 35 × 27 arcmin<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup> |
| Radio brightness | 240 Jy at 1 GHz; spectral index 0.37<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup> |
| Distance | H I absorption suggests 3.0 kpc; optical absorption 2.1 or 2.7 kpc; H<sub>2</sub> emission 2.8 kpc<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup> |
| Morphology | Mixed type: radio shell, centrally concentrated thermal X-rays, pulsar wind nebula<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup> |

## Discovery and naming

Its Galactic-coordinate name is written both G34.6−0.5 and G34.7−0.4 in different catalogs; the Cambridge Galactic supernova remnant catalog notes that the object "has been called G34.6−0.5."<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup>

## Radio morphology

In the radio band W44 appears as an asymmetric, nearly elliptical bright shell. The Cambridge catalog describes the shell as distorted and brighter to the east, with a pulsar and associated nebula within it.<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup> Early mapping work traced the source at successively higher resolution: Molonglo observations at 408 MHz with 3 arcminute resolution measured a flux density of 299 Jy, Arecibo measurements gave 540 ± 187 Jy at 430 MHz, and later Parkes, Effelsberg, and other maps resolved the shell structure at 2.7, 4.9, and 5 GHz.<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup>

The integrated radio spectrum is relatively flat for a shell remnant, with a spectral index of 0.37 (flux density falling as frequency to a low power) and a flux density of 240 Jy at 1 GHz, making it one of the brighter radio remnants in the Galactic plane.<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup>

## X-ray properties

X-ray emission from W44 is centrally concentrated with a thermal spectrum, and includes a pulsar wind nebula around the remnant's pulsar.<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup> Early Einstein Observatory observations found that the X-ray emission appears to be anticorrelated with the radio emission, consistent with the interior-filled X-ray morphology, and noted increased low-energy absorption toward the dense molecular cloud associated with the remnant.<sup>[2](https://www.cambridge.org/core/services/aop-cambridge-core/content/view/753097D79923BB0A351E020BE0C002E9/S0074180900033994a.pdf/div-class-title-einstein-observations-of-the-snrs-ic443-w44-and-w49b-div.pdf)</sup>

## Environment and pulsar

A pulsar lies within the boundary of the remnant, with an associated nebula seen in radio and X-ray observations.<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup>

Distance estimates from different methods span roughly 2 to 3 kpc: H I absorption suggests 3.0 kpc, optical absorption suggests 2.1 or 2.7 kpc, and H<sub>2</sub> emission suggests 2.8 kpc.<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup> At these distances the 35 × 27 arcmin shell corresponds to a remnant tens of light-years across.<sup>[1](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)</sup>

## As a mixed-morphology remnant

W44 belongs to the class of mixed-morphology supernova remnants, objects showing considerable overlap in their properties, in which a radio shell surrounds bright interior thermal X-rays.<sup>[3](https://seti.berkeley.edu/exotica/BL_Exotica_20E_Notes.pdf)</sup> This combination contrasts with the more common shell-type remnants, whose X-ray emission follows the radio limb brightening. The centrally filled thermal X-rays, radiative recombination continua, and molecular-cloud association shown by W44 are the characteristics that define this class.<sup>[3](https://seti.berkeley.edu/exotica/BL_Exotica_20E_Notes.pdf)</sup>

The remnant remains a target of ongoing observation: amateur radio-telescope groups have recorded it repeatedly, with observations on 5 and 8 December 2022 and again in 2023, and it appears as a calibrated source in modern survey catalogs such as GLOSTAR, which lists its extent as Galactic longitude 34.390 to 34.930 and latitude −0.760 to −0.093.<sup>[4](https://radiotelescopelavillette.wordpress.com/activite-en-2023/)</sup><sup> • </sup><sup>[5](https://elib.dlr.de/207140/2/aa49885-24.pdf)</sup>

## References

1. [G34.7-0.4 (W44), A Catalogue of Galactic Supernova Remnants, Mullard Radio Astronomy Observatory, Cambridge](https://www.mrao.cam.ac.uk/surveys/snrs/snrs.G34.7-0.4.html)
2. [Einstein Observations of the SNRs IC 443, W44 and W49B](https://www.cambridge.org/core/services/aop-cambridge-core/content/view/753097D79923BB0A351E020BE0C002E9/S0074180900033994a.pdf/div-class-title-einstein-observations-of-the-snrs-ic443-w44-and-w49b-div.pdf)
3. [Notes on type: mixed morphology supernova remnants, Berkeley SETI Research Center Exotica catalog](https://seti.berkeley.edu/exotica/BL_Exotica_20E_Notes.pdf)
4. [Activité en 2023, Radiotélescope du Parc de La Villette](https://radiotelescopelavillette.wordpress.com/activite-en-2023/)
5. [GLOSTAR: Radio Source Catalog IV, Astronomy & Astrophysics](https://elib.dlr.de/207140/2/aa49885-24.pdf)

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*Topic: Encyclopedia › Physical world and mathematics › Astronomy › Stars and galaxies › Nebulae and the interstellar medium › Named nebulae › Supernova remnants*

*Initially written Oct 15, 2026 · Edited: Oct 25, 2026*

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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license