Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. 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"

32688 results found.

  1. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  2. GRB 260424B: AstroSat CZTI detection
  3. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  4. EP260429a: LCO optical upper limits
  5. EP260430a: LCO optical upper limits
  6. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  7. Fermi GRB 260429A: Global MASTER-Net observations report
  8. EP260430a: Global MASTER-Net observations report
  9. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  10. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  11. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  12. GRB 260428A: AstroSat CZTI detection
  13. Fermi GRB 260428A: Global MASTER-Net observations report
  14. EP260416a: Mondy and Terskol optical upper limits
  15. GRB 260424B: Glowbug gamma-ray detection of a short burst
  16. GRB 260424B: COLIBRÍ optical upper limit
  17. Konus-Wind detection of GRB 260424B
  18. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  19. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  20. IPN triangulation of GRB 260424B (short)
  21. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  22. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  23. GRB 260401A: cubesat Avion detection
  24. EP260321a: Upper limits from ATCA radio observations
  25. GRB 260421B: Kilonova-Catcher optical afterglow detection
  26. GRB 260421B: Insight-HXMT/HE detection
  27. The EP-WXT trigger 01709258652: Mondy optical observations
  28. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  29. EP260416a: Mondy optical observations
  30. GRB 260421B: SVOM/ECLAIRs refined analysis
  31. GRB 260421B: 3.6m DOT optical observation
  32. EP260416a: ZTSh R band observations
  33. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  34. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  35. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  36. GRB 260419A: AstroSat CZTI detection
  37. GRB 260421B: SVOM/GRM observation
  38. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  39. GRB 260421B: EP-FXT follow-up observation
  40. GOTO26djh/AT2026jpw: ATCA radio detection
  41. GRB 260421B: J-band upper limit with WINTER
  42. GRB 260421B: LCO optical counterpart detection
  43. GRB 260421B: Fermi GBM Observation
  44. GRB 260421A: AstroSat CZTI detection
  45. GOTO26djh/AT2026jpw: radio detection at 15GHz
  46. GRB 260412A: SVOM/ECLAIRs refined analysis
  47. GRB 260421B: SVOM/VT optical observations
  48. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  49. GRB 260310A: Late-time Chandra X-ray Detection
  50. GRB 260418A: Insight-HXMT/HE detection
  51. EP260416a: 1.3m DFOT optical observation
  52. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  53. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  54. Fermi GRB 260421C: Global MASTER-Net observations report
  55. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  56. Fermi GRB 260421B: Global MASTER-Net observations report
  57. GRB 260421B: BOOTES-7 early optical afterglow detection
  58. GRB 260421B: LCO optical afterglow confirmation
  59. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  60. GRB 260421B: TRT optical counterpart detection
  61. GRB 260421B: SVOM detection of a long burst
  62. Fermi GRB 260421A: Global MASTER-Net observations report
  63. EP260321a: VLA radio follow-up
  64. GRB 260412A: LCOGT Optical Upper Limits
  65. EP260416a: Optical follow-up observations with Kinder
  66. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  67. EP-WXT trigger 01709260303: KAIT optical observations
  68. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  69. GRB 260417A: SVOM/GRM observation
  70. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  71. EP260417a: GROWTH-India Telescope optical upper limit
  72. Fermi GRB 260417B: Global MASTER-Net observations report
  73. EP260417b: GROWTH-India Telescope optical upper limit
  74. EP260416a: Ondrejov D50 optical detection
  75. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  76. EP260417a: Global MASTER-Net observations report
  77. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  78. EP260416a: NOT tentative spectroscopic redshift of z =1.909
  79. EP260416a: GMG Optical Observation
  80. Fermi GRB 260417A: Global MASTER-Net observations report
  81. Konus-Wind detection of GRB 260411B
  82. GRB 260417A: AstroSat CZTI detection
  83. IPN triangulation of GRB 260411B
  84. EP260416a: LCO observations confirm end of flaring phase
  85. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  86. EP260417a: TRT optical counterpart detection
  87. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  88. EP-WXT trigger 01709259586: KAIT optical observations
  89. EP260416a: KAIT optical upper limit
  90. GRB 260414A: Insight-HXMT/HE detection
  91. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  92. EP260416a: WFST optical observations and rebrightening
  93. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  94. EP260416a: SVOM/VT optical observation
  95. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  96. GRB 260415B: Glowbug gamma-ray detection
  97. GRB 260411B: Glowbug gamma-ray detection
  98. GRB 260415A: Insight-HXMT/HE detection
  99. EP260416a: COLIBRÍ optical counterpart candidate
  100. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw

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