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. GRB 210222B: REM observations of the optical/NIR afterglow
  2. Fermi trigger No 635922820: Global MASTER-Net observations report
  3. GRB 210222B: Zeiss-1000 of Koshka observatory, optical observations
  4. GRB 210222B: Swift/UVOT Detection
  5. GRB 210218A: Swift/UVOT observations
  6. GRB 210217A: Swift/UVOT Detection
  7. GRB 210222B: MASTER OT observation
  8. GRB 210222B: NEXT early optical afterglow observations
  9. GRB 210222B: GOTO confirmation of afterglow detection
  10. GRB210222B: BOOTES-1 optical afterglow detection
  11. Swift GRB210222.94: Global MASTER-Net observations report
  12. GRB 210218A: Swift-XRT observations
  13. uGMRT radio detection of GRB 210204A
  14. GRB 210212A: Lowell Discovery Telescope observations
  15. GRB 210217A: Liverpool Telescope First Hour Observations
  16. GRB 210217A: KAIT Optical Observations
  17. GRB 210218A: NEXT optical upper limit
  18. ZTF21aakruew/AT2021cwd: GROND observations
  19. GRB 210212A: REM early-time optical/NIR upper limits
  20. GRB 210205A: observations with the 3.6m DOT, a potential dark burst?
  21. GRB 210217A: NEXT early optical afterglow observations
  22. GRB 210212A: Mondy optical observations
  23. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued Assy and Mondy optical observations
  24. IceCube-210210A: Two Additional Optical Candidate Counterparts Found by DECam
  25. GRB 210208A: 1.3m DFOT Optical upper limit
  26. GRB 210211A: ePESSTO+ NTT optical observations
  27. GRB 210212B: Swift ToO observations
  28. GRB 210212B (TF21aakruew/AT2021cwd): Assy optical observations
  29. GRB 210212A: 1.3m DFOT Optical upper limit
  30. GRB 210212A: Gemini South optical observations
  31. Fermi GRB 210213A: Global MASTER-Net observations report
  32. IceCube Alert 210213.78: Global MASTER-Net observations report
  33. IceCube-210210A: Four Candidate Optical Counterparts from DECam Observations
  34. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued CrAO and AbAO optical observations
  35. GRB 210212A: Possible host galaxy counterpart with the NOT
  36. Swift GRB 210212A: Global MASTER-Net observations report
  37. GRB 210212A: Swift/UVOT Upper Limits
  38. GRB 210204A: observations with the 3.6m Devasthal Optical Telescope and possible jet break
  39. GRB 210210A : 1.3m DFOT optical observations
  40. GRB 210211A: Swift/UVOT Detection
  41. Swift-XRT observations of IceCube-210210A
  42. GRB 210211A: MASTER optical observation of REM OT
  43. GRB 210210A: CAHA detection and likely jet break
  44. GRB 210211A: REM optical/NIR afterglow detection
  45. Fermi-LAT Gamma-ray Observations of IceCube-210210A
  46. Swift GRB210211.36: Global MASTER-Net observations report
  47. Fermi trigger No 634659312: Global MASTER-Net observations report
  48. IceCube Alert 210210.50: Global MASTER-Net observations report
  49. Fermi GRB 210210B: Global MASTER-Net observations report
  50. IceCube-210210A: Upper limits from Fermi-GBM Observations
  51. IceCube-210210A: Two Candidate Counterparts from the Zwicky Transient Facility
  52. Swift GRB 210209A: Global MASTER-Net observations report
  53. GRB 210210A: Swift/UVOT Detection
  54. GRB 210112A: LBT host detection and correction to GCN 29319 (CAHA observations)
  55. GRB 210209A: Swift/UVOT Upper Limits
  56. GRB 210210A: MASTER afterglow observation
  57. ZTF21aahifke/AT2021clk: ZTF discovery of an optical fast transient (possible afterglow)
  58. Swift GRB 210210A: Global MASTER-Net observations report
  59. GRB 210207B: Continued LCO Observations
  60. GRB 210104A: LBT observations
  61. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued Mondy optical observations
  62. GRB 210207B: Swift/UVOT Detection
  63. GRB 210204A: LBT observations and jet break
  64. GRB 210207B: LCO Optical Afterglow Detection
  65. GRB 210207B: KAIT Optical Observations
  66. GRB 210207B: AGILE observations
  67. GRB 210207B: AbAO optical upper limit
  68. GRB 210207B: optical detection with 3.6m Devasthal Optical Telescope
  69. Fermi GRB 210207A: Global MASTER-Net observations report
  70. GRB 210204A (ZTF21aagwbjr/AT2021buv): Mondy and AbAO optical observations
  71. GRB 210204A: Optical Observations from HCT
  72. GRB 210204A / ZTF21aagwbjr: Swift-XRT observations
  73. GRB 210204A: Swift ToO observations
  74. VLT/X-shooter redshift of 1.466 for ZTF21aagwbjr/AT2021buv, strengthening its association with GRB 210204A
  75. GRB 210205A: Swift/UVOT Upper Limits
  76. Swift GRB 210205A: Global MASTER-Net observations report
  77. Fermi GRB 210204B: Global MASTER-Net observations report
  78. Fermi GRB 210204A: Global MASTER-Net observations report
  79. Fermi GBM Observations of a bright burst from SGR J1935+2154
  80. Fermi GRB 210202A: Global MASTER-Net observations report
  81. Fermi trigger No 633963272: Global MASTER-Net observations report
  82. Fermi trigger No 633879387: Global MASTER-Net observations report
  83. GECAM observations of SGR 1935+2154
  84. Continued Chandra observations of GW170817 at ~3.3 years since merger
  85. Fermi GBM Observations of SGR J1935+2154
  86. ZTF21aaeyldq: Observations with the 3.6m DOT
  87. GRB 210120A: Fermi GBM detection
  88. Fermi trigger No 633348010: Global MASTER-Net observations report
  89. HAWC Transient event on 2021/01/25
  90. Fermi trigger No 633257525: Global MASTER-Net observations report
  91. GRB 210120A : 1.3m DFOT optical observations
  92. ZTF21aaeyldq: GROND and CAHA jet break confirmation
  93. ZTF20aaeyldq: VLA radio detection
  94. GRB 210120A(MASTER OT J105242.66+152355.0 / AT2021axc): Mondy optical observations
  95. GRB 210120A: MASTER OT (possibly) discovery
  96. GRB 210104A: 3.6m DOT optical upper limit
  97. Fermi GRB 210120A: Global MASTER-Net observations report
  98. GRB 210112A: 3.6m DOT optical detection
  99. ZTF21aaeyldq: GROND observations
  100. ZTF21aaeyldq: LBT near-infrared observations

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