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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"

24674 results found.

  1. GRB 241010A: Enhanced Swift-XRT position
  2. GRB 241010A: LCO optical observations
  3. GRB 241010A: Swift detection of a burst with an optical counterpart
  4. Fermi-LAT Gamma-ray Observations of IceCube-241006A
  5. GRB 241006A: Swift-BAT refined analysis
  6. LIGO/Virgo/KAGRA S241009l: Updated Sky localization
  7. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  8. GRB 241008A: Fermi GBM Observation
  9. GRB 241002B: Swift-XRT afterglow detection
  10. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  11. GRB 241002A: NOT optical upper limits
  12. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  13. GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
  14. IceCube-241006A: No candidates from the Zwicky Transient Facility
  15. GRB 241006A: GRANDMA optical upper limits
  16. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  17. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  18. GRB 240910A: LBT optical observations
  19. GRB 241006A: Swift-XRT refined Analysis
  20. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  21. GRB 241006A: PRIME near-infrared upper limits
  22. GRB 241006A: Swift/UVOT Upper Limits
  23. LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
  24. GRB 241001A: Swift-XRT afterglow detection
  25. GRB 241006A: Enhanced Swift-XRT position
  26. GRB 241006A: Swift detection of a burst
  27. GRB 240930B: SVOM/C-GFT optical upper limit
  28. LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
  29. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  30. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  31. GRB 241002B: Fermi GBM Observation
  32. GRB 241002B: Swift-XRT observations
  33. GRB 241002C: SVOM/C-GFT optical upper limit
  34. GRB 241002A: Swift-BAT refined analysis
  35. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  36. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  37. GRB 241002B: PRIME near-infrared detection
  38. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  39. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  40. IPN triangulation of GRB 240930B / EP 240930a
  41. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  42. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  43. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  44. GRB 241002C : MITSuME Akeno optical upper limits
  45. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  46. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  47. GRB241001A: REM optical/NIR upper limits
  48. LIGO/Virgo/KAGRA S241002e: Updated Sky localization
  49. GRB 241002A: Swift/UVOT Upper Limits
  50. EP240930a: Liverpool Telescope observations
  51. GRB 241002A: Swift-XRT refined Analysis
  52. GRB 241002A: LCOGT Optical Upper Limits
  53. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  54. GRB 241001A: Swift/UVOT Detection
  55. GRB 240929A: Liverpool Telescope prompt followup observations
  56. GRB 241001A: Swift-XRT observations
  57. GRB241001A: optical afterglow candidate
  58. GRB 241002A: Enhanced Swift-XRT position
  59. GRB 241001A: BOOTES-6/DPRT optical upper limit
  60. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  61. GRB 241002A: Swift detection of a burst
  62. LIGO/Virgo/KAGRA S240930du: Updated Sky localization
  63. GRB 240930B: Fermi GBM Observation
  64. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  65. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  66. EP240930a: EP-WXT detection of a fast X-ray transient
  67. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
  68. LIGO/Virgo/KAGRA S240930du: Identification of a GW compact binary merger candidate
  69. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  70. LIGO/Virgo/KAGRA S240930df: 1 counterpart neutrino candidate event from an IceCube neutrino search
  71. AMON NuEM 240926A: Swift XRT Follow-up
  72. GRB 240929A : Leavitt Observatory optical upper limit
  73. GRB 240825A: LBT optical observations
  74. GRB 240928A: SVOM/GRM observation
  75. LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
  76. Fermi trigger No 749339671: Global MASTER-Net observations report
  77. GRB 240929A long GRB detected by INTEGRAL
  78. GRB 240929A: BALROG localization (Fermi Trigger 749332209 / GRB 240929826)
  79. Swift Trigger 1256950 is probably not a GRB
  80. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  81. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  82. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  83. NuEm-240926A / IC240926A: BZQJ0955+4532 ~0.6m optical decay and rebrightening detection by MASTER
  84. GRB 240926A: SVOM/GRM observation
  85. Konus-Wind detection of GRB 240905B
  86. EP240919a / GRB 240919A: SVOM/VT upper limit
  87. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  88. EP240918b and EP240918c: EP-FXT follow-up observations
  89. LIGO/Virgo/KAGRA S240925n: Updated Sky localization and Source Classification
  90. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  91. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  92. LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
  93. GRB 240905B: VZLUSAT-2 detection
  94. LIGO/Virgo/KAGRA S240922df: Updated Sky localization
  95. LIGO/Virgo/KAGRA S240920dw: Updated Sky localization
  96. LIGO/Virgo/KAGRA S240921cw: Updated Sky localization
  97. LIGO/Virgo/KAGRA S240924a: Updated Sky localization
  98. LIGO/Virgo/KAGRA S240920bz: Updated Sky localization and Source Classification
  99. LIGO/Virgo/KAGRA S240923ct: Updated Sky localization and Source Classification
  100. LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate

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