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"

45673 results found.

  1. GRB 260401A: cubesat Avion detection
  2. GRB 260424A: AstroSat CZTI detection of a long burst
  3. EP260321a: Upper limits from ATCA radio observations
  4. GRB 260421B: Kilonova-Catcher optical afterglow detection
  5. GRB 260421B: Insight-HXMT/HE detection
  6. The EP-WXT trigger 01709258652: Mondy optical observations
  7. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  8. EP260416a: Mondy optical observations
  9. GRB 260421B: SVOM/ECLAIRs refined analysis
  10. GRB 260421B: 3.6m DOT optical observation
  11. EP260416a: ZTSh R band observations
  12. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  13. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  14. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  15. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  16. GRB 260419A: AstroSat CZTI detection
  17. GRB 260421B: SVOM/GRM observation
  18. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  19. GRB 260421B: EP-FXT follow-up observation
  20. The EP-WXT trigger 01709260362 is likely a flaring star
  21. GOTO26djh/AT2026jpw: ATCA radio detection
  22. GRB 260421B: J-band upper limit with WINTER
  23. GRB 260421B: LCO optical counterpart detection
  24. GRB 260421B: Fermi GBM Observation
  25. Fermi Gamma-ray Burst Monitor trigger 798482368/260421694 is not a GRB
  26. GRB 260421A: AstroSat CZTI detection
  27. GOTO26djh/AT2026jpw: radio detection at 15GHz
  28. GRB 260412A: SVOM/ECLAIRs refined analysis
  29. GRB 260421B: SVOM/VT optical observations
  30. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  31. GRB 260310A: Late-time Chandra X-ray Detection
  32. GRB 260418A: Insight-HXMT/HE detection
  33. EP260416a: 1.3m DFOT optical observation
  34. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  35. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  36. Fermi GRB 260421C: Global MASTER-Net observations report
  37. GRB 260421C: Fermi GBM Final Real-time Localization
  38. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  39. Fermi GRB 260421B: Global MASTER-Net observations report
  40. GRB 260421B: BOOTES-7 early optical afterglow detection
  41. GRB 260421B: LCO optical afterglow confirmation
  42. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  43. GRB 260421B: TRT optical counterpart detection
  44. GRB 260421B: SVOM detection of a long burst
  45. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  46. GRB 260421B: Fermi GBM Final Real-time Localization
  47. Fermi GRB 260421A: Global MASTER-Net observations report
  48. GRB 260421A: Fermi GBM Final Real-time Localization
  49. EP260321a: VLA radio follow-up
  50. GRB 260412A: LCOGT Optical Upper Limits
  51. The EP-WXT trigger 01709260314 is likely a flaring star
  52. EP260416a: Optical follow-up observations with Kinder
  53. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  54. EP-WXT trigger 01709260303: KAIT optical observations
  55. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  56. The EP-WXT trigger 01709260303 is likely a flaring star
  57. GRB 260417A: SVOM/GRM observation
  58. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  59. GRB 260419B: Fermi GBM Final Real-time Localization
  60. GRB 260419A: Fermi GBM Final Real-time Localization
  61. Fermi trigger No 798275385: Global MASTER-Net observations report
  62. EP260417a: GROWTH-India Telescope optical upper limit
  63. Fermi GRB 260417B: Global MASTER-Net observations report
  64. EP260417b: GROWTH-India Telescope optical upper limit
  65. EP260416a: Ondrejov D50 optical detection
  66. GRB 260418B: Fermi GBM Final Real-time Localization
  67. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  68. EP260417a: Global MASTER-Net observations report
  69. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  70. EP260416a: NOT tentative spectroscopic redshift of z =1.909
  71. GRB 260418A: Fermi GBM Final Real-time Localization
  72. EP260416a: GMG Optical Observation
  73. Fermi GRB 260417A: Global MASTER-Net observations report
  74. Konus-Wind detection of GRB 260411B
  75. GRB 260417B: Fermi GBM Final Real-time Localization
  76. GRB 260417A: AstroSat CZTI detection
  77. IPN triangulation of GRB 260411B
  78. EP260416a: LCO observations confirm end of flaring phase
  79. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  80. EP260417a: TRT optical counterpart detection
  81. EP260417a: Einstein Probe detection of an X-ray transient
  82. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  83. EP260417b: Einstein Probe detection of a fast X-ray transient
  84. EP-WXT trigger 01709259586: KAIT optical observations
  85. EP260416a: KAIT optical upper limit
  86. GRB 260414A: Insight-HXMT/HE detection
  87. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  88. EP260416a: WFST optical observations and rebrightening
  89. GRB 260417A: Fermi GBM Final Real-time Localization
  90. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  91. EP260416a: SVOM/VT optical observation
  92. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  93. GRB 260415B: Glowbug gamma-ray detection
  94. GRB 260411B: Glowbug gamma-ray detection
  95. GRB 260415A: Insight-HXMT/HE detection
  96. EP260416a: COLIBRÍ optical counterpart candidate
  97. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  98. EP260416a: Global MASTER-Net observations report
  99. EP260416a: Einstein Probe detection of an X-ray transient
  100. GOTO26djh/AT2026jpw : MASTER OT observation

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