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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

32484 results found.

  1. GRB 241009A: Swift ToO observations
  2. LIGO/Virgo/KAGRA S241009l: Updated Sky localization
  3. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  4. GRB 241008A: Fermi GBM Observation
  5. GRB 241008A: Fermi-LAT detection
  6. GRB 241002B: Swift-XRT afterglow detection
  7. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  8. GRB 241002A: NOT optical upper limits
  9. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  10. Fermi GRB 241008A: Global MASTER-Net observations report
  11. IceCube-241006A: No candidates from the Zwicky Transient Facility
  12. GRB 241006A: GRANDMA optical upper limits
  13. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  14. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  15. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  16. GRB 240910A: LBT optical observations
  17. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  18. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  19. GRB 241006A: PRIME near-infrared upper limits
  20. GRB 241006A: Swift/UVOT Upper Limits
  21. GRB 241006A: SVOM/VT follow-up and optical upper limit
  22. LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
  23. GRB 240930B: SVOM/C-GFT optical upper limit
  24. LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
  25. GRB 240930B / EP 240930a: SVOM/GRM observation
  26. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  27. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  28. GRB 241002B: Fermi GBM Observation
  29. GRB 241002B: Swift-XRT observations
  30. GRB 241002C: SVOM/C-GFT optical upper limit
  31. GRB 241002A: Swift-BAT refined analysis
  32. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  33. GRB 241002B: Swift ToO observations
  34. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  35. Konus-Wind detection of GRB 240926A
  36. GRB 241002B: PRIME near-infrared detection
  37. GRB 241002C: Swift ToO observations
  38. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  39. IPN triangulation of GRB 240930B / EP 240930a
  40. GRB 241001A : SVOM/VT optical detection
  41. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  42. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  43. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  44. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  45. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  46. GRB 241002C : MITSuME Akeno optical upper limits
  47. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  48. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  49. GRB241001A: REM optical/NIR upper limits
  50. LIGO/Virgo/KAGRA S241002e: Updated Sky localization
  51. GRB 241002A: Swift/UVOT Upper Limits
  52. EP240930a: Liverpool Telescope observations
  53. GRB 241002A: LCOGT Optical Upper Limits
  54. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  55. GRB 241001A: Swift/UVOT Detection
  56. GRB 241001A: VLT/X-shooter redshift
  57. GRB 241002B: GOTO optical counterpart candidate
  58. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  59. GRB 241001A: correction to GCN 37667
  60. GRB 240929A: Liverpool Telescope prompt followup observations
  61. Fermi GRB 241002B: Global MASTER-Net observations report
  62. GRB 241001A: Swift-XRT observations
  63. GRB241001A: optical afterglow candidate
  64. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  65. LIGO/Virgo/KAGRA S240930du: Updated Sky localization
  66. GRB 240930B: Fermi GBM Observation
  67. GRB 241001A: Swift ToO observations
  68. GRB 240930B: GRBAlpha detection
  69. GRB 240929A: GRBAlpha detection
  70. EP240930a : KAIT optical upper limit
  71. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  72. EP240930a: EP-FXT follow-up observation update
  73. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  74. EP240930a: GOTO optical upper limits
  75. GRB 240929A: SVOM/GRM observation
  76. EP EP240930a: Global MASTER-Net observations report
  77. EP240930a: EP-WXT detection of a fast X-ray transient
  78. LIGO/Virgo/KAGRA S240930du: Identification of a GW compact binary merger candidate
  79. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  80. AMON NuEM 240926A: Swift XRT Follow-up
  81. GRB 240929A : Leavitt Observatory optical upper limit
  82. Fermi GRB 240930B: Global MASTER-Net observations report
  83. IPN triangulation of GRB 240926A
  84. GRB 240825A: LBT optical observations
  85. Fermi GRB 240930A: Global MASTER-Net observations report
  86. Fermi Gamma-ray Burst Monitor trigger 749362078/240930172 (GRB 240930A) is not a GRB
  87. LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
  88. GRB 240929A long GRB detected by INTEGRAL
  89. Fermi GRB 240929A: Global MASTER-Net observations report
  90. Konus-Wind detection of GRB 240912A
  91. EP trigger ID 01709059262: Lick/Kast spectroscopy with 3 m Shane telescope
  92. NuEm-240926A / IC240926A: BZQJ0955+4532 ~0.6m optical decay and rebrightening detection by MASTER
  93. Konus-Wind detection of GRB 240905B
  94. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  95. EP240919a / GRB 240919A: SVOM/VT upper limit
  96. EP240918b and EP240918c: EP-FXT follow-up observations
  97. LIGO/Virgo/KAGRA S240925n: Updated Sky localization and Source Classification
  98. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  99. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  100. LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate

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