Letter | Published:

Observations of a transient X-ray source with regular periodicity of 6.75 min


DURING planned observations, by the satellite Ariel V, of the X-ray source Cen X-3 (3U1118-60), a previously unreported source nearby was detected by the collimated proportional counter of 100 cm2 provided by the Mullard Space Science Laboratory. The source was monitored over a period of 39 d between December 19, 1974, and January 27, 1975. Here we report measurements of the light curve, spectrum and of a regular variability with period of 6.755 ± 0.010 min. The position of the source is given in the accompanying letter1.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Eyles, C. J., Skinner, G. K., Willmore, A. P., and Rosenberg, F. D., Nature, 254, 577 (1975).

  2. 2

    Brown, R. L., and Gould, J., Phys. Rev. D., 1, 2252 (1970).

  3. 3

    Daltabuit, E., and Meyer, S., Astr. Astrophys., 20, 415–424 (1972).

  4. 4

    Sanford, P. W., Proc. R. Soc., A 340, 411–422 (1974).

  5. 5

    Pringle, J. E., Nature, 247, 21–22 (1974).

  6. 6

    Davidsen, A., and Ostriker, J. P., Astrophys. J., 189, 331–338 (1974).

  7. 7

    Schreier, E., Levinson, R., Gursky, H., Kellogg, E., Tananbaum, H., and Giacconi, R., Astrophys. J., 172, L79–L89 (1972).

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.