Skip to main content
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

21140 results found.

  1. Fermi GRB 210119A: Global MASTER-Net observations report
  2. ZTF21aaeyldq CAHA 2.2m detection and power-law decay
  3. Fermi trigger No 632573937: Global MASTER-Net observations report
  4. ZTF21aaeyldq: KPED observations
  5. ZTF21aaeyldq (AT2021any): Detection of X-ray Emission with Swift/XRT
  6. ZTF21aaeyldq: 2.2m CAHA BVRI optical observations
  7. GRB 201221D: near-infrared observation with LBT
  8. ZTF21aaeyldq: NOT optical observations
  9. ZTF21aaeyldq: Lowell Discovery Telescope observations
  10. ZTF21aaeyldq: observations with the 3.6m Devasthal Optical Telescope
  11. GRB 201015A: evidence of supernova in LBT spectra
  12. ZTF Discovery of ZTF21aaeyldq (AT2021any): a Hostless, Young, and Rapidly Fading Transient
  13. GRB 210104A: JCMT SCUBA-2 sub-mm observations
  14. GRB 210112A: Swift/UVOT Detection
  15. GRB 210112A: Mondy optical observations
  16. GRB 210112A: 1.3m DFOT Optical upper limit
  17. GRB 210112A: OSN second epoch, decay
  18. GRB 210112A: OSN Reddened Afterglow Detection
  19. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-210111A
  20. GRB 210104A: Mondy optical observations, light curve
  21. MAXI GRB210110.64: Global MASTER-Net observations report
  22. GRB 210104A: Assy continued optical observations, correction to GCN circ. 29265
  23. GRB 201227A: continued Chilescope confirmation of variability of possible optical counterpart, redshift estimating
  24. GRB 210104A: SAO RAS optical observations
  25. GRB 201227A: ASIM observation
  26. GRB 210104A: GMG observations
  27. Fermi trigger No 631602681: Global MASTER-Net observations report
  28. GRB 210102B: further Swift-XRT observations
  29. GRB 210102B: Assy optical afterglow identification
  30. Fermi trigger No 631584650: Global MASTER-Net observations report
  31. GRB 210104A: Assy continued optical observations
  32. Fermi GRB 210105A: Global MASTER-Net observations report
  33. GW170817: HST observations at 3.4 years from merger
  34. GRB 210104A: early ATLAS detections of the bright afterglow
  35. GRB 210104B: Swift/UVOT Upper Limits
  36. GRB 210104B: Assy optical upper limit
  37. GRB 210104A: DOAO optical afterglow observations
  38. GRB 210104A: Nanshan/NEXT optical powerlaw decay
  39. GRB 210104B: Nanshan/NEXT optical upper limit
  40. GRB 210104B: BOOTES network optical upper limit
  41. GRB 210104A: Swift/UVOT Detection
  42. GRB 210102B: Tiled Swift observations
  43. Swift GRB210104.88: Global MASTER-Net observations report
  44. GRB 210102B: Assy optical observations
  45. Fermi GRB 210104A: Global MASTER-Net observations report
  46. GRB 210104A: Assy optical observations
  47. GRB 210104A: BOOTES-4/MET early optical afterglow detection
  48. GRB 210104A: GWAC-F60A optical afterglow observations
  49. GRB 210102B: Swift-XRT observations
  50. Fermi GRB 210102C: Global MASTER-Net observations report
  51. Swift GRB 210102C: Global MASTER-Net observations report
  52. MAXI GRB210102.38: Global MASTER-Net observations report
  53. GRB 210102B: Tiled Swift observations
  54. Fermi GRB 210101A: Global MASTER-Net observations report
  55. Swift GRB210102.01: Global MASTER-Net observations report
  56. Fermi trigger No 631226368: Global MASTER-Net observations report
  57. Fermi trigger No 631119348: Global MASTER-Net observations report
  58. Fermi trigger No 631113166: Global MASTER-Net observations report
  59. GRB 201229A: Swift/UVOT Detection
  60. Fermi trigger No 631118376: Global MASTER-Net observations report
  61. Fermi trigger No 631104264: Global MASTER-Net observations report
  62. GRB 201216C: TSHAO, Terskol, Mondy optical upper limits
  63. Baksan Neutrino Observatory Alert 201230.40: Global MASTER-Net observations report
  64. GRB 201227A: Chilescope optical observations, possible optical counterpart
  65. GRB 201227A: GRAWITA VST-ESO PARANAL observations
  66. GRB 201229A: AbAO optical afterglow detection, TSHAO optical upper limit
  67. GRB 201229A: SAO RAS optical observations
  68. GRB 201227A: Swift-XRT observations
  69. GRB 201104B: Maidanak and CrAO optical observations
  70. Fermi GRB 201229B: Global MASTER-Net observations report
  71. GRB 201020B: Assy, Koshka, Mondy and Maidanak optical observations
  72. Baksan Neutrino Observatory Alert 201228.36: Global MASTER-Net observations report
  73. Fermi GRB 201228B: Global MASTER-Net observations report
  74. GRB 201227A: Tiled Swift observations
  75. GRB 201227A: Swift ToO observations
  76. ZTF20acozryr/AT2020yxz (GRB 201103B): Maidanak optical observations
  77. Fermi trigger No 630681391: Global MASTER-Net observations report
  78. GRB 201223A: Swift/UVOT Detection
  79. GRB 201223A: HCT optical upper limit
  80. Baksan Neutrino Observatory Alert 201225.54: Global MASTER-Net observations report
  81. GRB 201223A: AbAO optical observations
  82. GRB 201223A: 1.3m DFOT and 1.04m ST optical observations
  83. IceCube-201222A: No Candidate Counterparts from the Zwicky Transient Facility
  84. GRB 201223A: NOT optical upper limit and NEXT powerlaw decay
  85. GRB 201223A: Mondy and Kitab optical observations
  86. GRB 201223A: GWAC-F60A optical afterglow observations
  87. GRB 201223A: iTelescope optical afterglow observations
  88. Baksan Neutrino Observatory Alert 201223.60: Global MASTER-Net observations report
  89. GRB 201223A: BOOTES-4/MET early optical observation
  90. GRB 201223A: Nanshan/NEXT early optical afterglow detection
  91. Swift GRB201223.75: Global MASTER-Net observations report
  92. Swift-XRT observations of Icecube 201222A
  93. GRB 201221A: REM early-time afterglow detection
  94. GRB 201221D: 3.6m DOT optical observations
  95. IceCube-201221A: Upper limits from Insight-HXMT/HE observations
  96. Fermi trigger No 630389391: Global MASTER-Net observations report
  97. GRB 201221D: SMA submm observation
  98. Fermi GRB 201222B: Global MASTER-Net observations report
  99. GRB 201221D: MMT MMIRS detection of marginally extended source
  100. GRB 201221D: LCOGT upper limits

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov