---
title: "NGC 4842A"
url: "https://spacecatalog.org/object/ngc-4842a"
release: "DR1"
licence: "CC-BY-SA-4.0"
citation: "SpaceCatalog. NGC 4842A [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/ngc-4842a"
---

# NGC 4842A

NGC 4842A is an elliptical [galaxy](https://spacecatalog.org/galaxies) E in the constellation [Coma Berenices](https://spacecatalog.org/constellation/coma-berenices), 360.4 Mly from Earth, shining at apparent magnitude 15.22 (B). Other catalogues list it as 2MASX J12573584+2729358, MCG +05-31-030 and SDSS J125735.85+272935.5, among 6 designations in total. It was discovered in 1865.

## At a glance

- **WHAT IT IS:** Elliptical galaxy
- **HOW FAR:** 360.4 Mly — A luminosity distance, from its redshift — how faint it looks. The light itself left 335 million years ago.
- **HOW BIG ON THE SKY:** 35″ — Small enough that the full Moon would cover it several times over.
- **HOW BRIGHT (B):** 15.22 — Faint: it takes a large telescope.
- **WHERE TO LOOK:** [Coma Berenices](https://spacecatalog.org/constellation/coma-berenices) — The patch of sky it sits in, as seen from Earth.

## Properties

| Quantity | Value |
| --- | --- |
| CLASS | Elliptical galaxy E |
| DISTANCE FROM EARTH | 360.4 Mly ±20 — by redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc |
| APPARENT MAGNITUDE (B) | 15.22 |
| CONSTELLATION | Coma Berenices |
| RIGHT ASCENSION (J2000) | 12h 57m 35.8s |
| DECLINATION (J2000) | +27° 29′ 35.7″ |
| DISCOVERED | 1865 |

## Catalogue data

### WHAT KIND OF THING IT IS

What the object is in itself, rather than how it happens to look from here.

| Field | Value |
| --- | --- |
| Hubble type | E |

### HOW BRIGHT IT IS

What the light adds up to, measured through one filter at a time. A magnitude is a brightness on a backwards scale — the smaller the number, the brighter the object.

| Field | Value |
| --- | --- |
| Apparent magnitude (B) | 15.22 |
| Apparent magnitude (J) | 11.88 |
| Apparent magnitude (H band) | 11.18 |
| Apparent magnitude (K) | 11.00 |
| Surface brightness | 22.91 mag/arcsec² |

### WHERE IT IS AND HOW IT MOVES

Position, motion across the sky and the size it covers on it. These are measurements of the object as seen from here, so every one of them depends on where here is.

| Field | Value |
| --- | --- |
| Radial velocity | 7223 km/s |
| Redshift (z) | 0.02439 |
| Redshift (z, CMB frame) | 0.0253157 |
| Major axis | 0.58′ |
| Minor axis | 0.57′ |
| Position angle | 70° |

### WHEN IT WAS FOUND

Who first saw it, from where, and by what method.

| Field | Value |
| --- | --- |
| Discovered by | Heinrich Louis d'Arrest |

### OTHER NAMES AND NUMBERS

The identifiers other catalogues file this object under, for anyone joining this data to theirs.

| Field | Value |
| --- | --- |
| OpenNGC type code | G |
| Wikidata item | Q1114827 |

## Also known as

- 2MASX: 2MASX J12573584+2729358
- MCG: MCG +05-31-030
- SDSS: SDSS J125735.85+272935.5
- SDSS: SDSS J125735.85+272935.6
- SDSS: SDSS J125735.86+272935.5
- UGC: UGC 08070 NOTES02

## Source

[OpenNGC](https://github.com/mattiaverga/OpenNGC) — CC-BY-SA-4.0

The producer asks: OpenNGC, Mattia Verga (github.com/mattiaverga/OpenNGC). Fields derived from it stay under CC BY-SA 4.0.

How this was made: https://spacecatalog.org/methods#source-openngc

## Cite this page

SpaceCatalog. NGC 4842A \[catalogue entry\]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/ngc-4842a

```bibtex
@misc{spacecatalog_ngc-4842a,
  author       = {{SpaceCatalog}},
  title        = {{NGC 4842A}},
  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
  year         = {2026},
  url          = {https://spacecatalog.org/object/ngc-4842a},
  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from OpenNGC.}
}
```

OpenNGC — CC-BY-SA-4.0

Acknowledgement the producer asks for: OpenNGC, Mattia Verga (github.com/mattiaverga/OpenNGC). Fields derived from it stay under CC BY-SA 4.0.

The page itself, with its pictures, the sky map and the observing tools: https://spacecatalog.org/object/ngc-4842a